Polymeric well treating method

ABSTRACT

Several new treatment processes and compositions for practicing these processes are provided which substantially alter the fluid flow and surface characteristics of porous permeable particulate formations, especially subterranean formations intersected by an oil well. The compositions of this invention also provide methods of increasing viscosity or gelling aqueous fluids, especially acids, which can be used to treat such earthen formations. Treatment of the earthen formations with the compositions of this invention can substantially modify the permeability and surface characteristics of the formation to prevent or reduce the flow of aqueous fluids, especially water and formation brines through that portion of the formation, thereby reducing the water-oil ratio of fluid flowing through or produced from that formation and in some cases enhancing the hydrocarbon production. The treatment of this invention uses branched organic polymers of a wide molecular weight range. The branches are preferably hydrophilic and the polymer contains bonding groups (e.g. ionic bonding groups) which serve to attract or repel a substrate, a particular formation, suspended solids, other polymers or segments, carrier fluid or a fluid to be treated.

This is a division of application Ser. No. 946,700, filed Sept. 28,1978, now abandoned.

Numerous methods have been used to treat earthen formations andespecially subterranean formations intersected by an oil well whichproduce water as well as oil or hydrocarbon. Production of the water orbrine reduces the value of the well since the water is normally unwantedand requires expensive methods for disposal. Likewise the penetration ofaqueous fluids into earthen formations is frequently undesired,especially in the drilling, completion or workover phases of an oil wellin which the filtrate entering certain formations from fluids used inthe well can damage the formation. In treating subterranean formationsfor these and other purposes, aqueous gels are frequently used forstimulation (e.g. acidizing and fracturing), completion (e.g. cementing,gravel packing and perforating), drilling, workover, grouting, mobilitycontrol, and water control. Several systems are also available toincrease the viscosity of aqueous fluids, such as acidic fluids.However, the previous methods and compositions present problems such asbeing temporary, unstable or possessing other problems.

Several of the numerous methods previously used to reduce the flow ofaqueous fluids into or out of such formations are described in thefollowing U.S. Pat. No. 3,393,912 to Sparlin et al; U.S. Pat. No.3,868,999 to Christopher et al; U.S. Pat. No. 3,830,302 to Dreher et al;U.S. Pat. No. 3,826,311 to Szabo et al; U.S. Pat. No. 3,820,603 toKnight et al; and U.S. Pat. No. 3,779,316 to Bott. Sparlin describes amethod for reducing the production water from oil wells by injectinginto the well a viscous oil containing a coupling agent selected fromphenolic and furan resins. Christopher describes a method for reducingthe water permeability of a formation as compared to the oilpermeability by injecting into a formation a slug of fluid comprising ahydrocarbon solvent, colloidal silica, water and a polymeric material.Dreher describes a method for reducing the water oil ratio of aproducing well by treating a formation with a combination of an aqueousorganic polyelectrolyte such as polyacrylamide and a cationicsurfactant. Szabo describes the use of a certain copolymer of(3-acrylamido-3-methyl)butyl trimethyl ammonium chloride and acrylamidehaving a molecular weight of at least 100,000 to reduce the waterproduction of fingering in a waterflooding process using emulsions of awater soluble anionic vinyl addition polymer and a water solublecationic polymer.

In addition to the above described prior art references numerousreferences describe methods of using, preparing and using polymers fortreating earthen formations. Selected patents and articles are listed asfollows:

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ARTICLES AND BOOKS

1. Barkman, J. H.; Abrams, A.; Darley, H. C. H.; and Hill, H. J.; "AnOil Coating Process to Stabilize Clays in Fresh Water FloodingOperation," SPE-4786, SPE of AIME Symposium on Formation Damage Control,New Orleans, La., Feb. 7-8, 1974.

2. Coppel, Claude F.; Jennings, Harley X.; and Reed, M. G.; "FieldResults From Wells Treated With Hydroxy-Aluminum," JOURNAL OF PETROLEUMTECHNOLOGY (September 1973) pp. 1108-1112.

3. Dow Chemical Company, "PEI Polymers . . . Infinite Modifications,Practical Versality," Copyrighted 1974.

4. Graham, John W.; Monoghan, P. H.; & Osoba, J. S.; "Influence ofPropping Sand Wettability of Productivity of Hydraulically Fractured OilWells," PETROLEUM TRANSACTIONS, AIME, Vol. 216 (1959).

5. Hower, Wayne F.; "Influence of Clays on the Production ofHydrocarbons," SPE-4785, SPE of AIME Symposium on Formation DamageControl, New Orleans, La., Feb. 7-8, 1974.

6. Hower, Wayne F.; "Adsorption of Surfactants on Montmorillonite,"CLAYS AND CLAY MINERALS, Pergamon Press (1970) Vol. 18, pp. 97-105.

7. Hoover, M. F., & Butler, G. B.; "Recent Advances in Ion-ContainingPolymers," J. POLYMER SCI, Symposium No. 45, 1-37 (1974).

8. Jackson, Kern C.; TEXTBOOK OF LITHOLOGY, McGraw-Hill Book Company(1970) (Library of Congress Catalogue Card No. 72-958LO) pp. 95-103.

9. Theng, B. K. G.; THE CHEMISTRY OF CLAY-ORGANIC REACTIONS, John Wiley& Son (1974) (Library of Congress Catalog Card No. 74-12524) pp. 1-16.

10. Veley, C. D.; "How Hydrolyzable Metal Ions Stabilize Clays ToPrevent Permeability Reduction," SPE-2188, 43rd Annual Fall Meeting ofSPE of AIME, Houston, Tex. (Sept. 29-Oct. 2, 1968).

11. Milchem Incorporated, "Milchem's SHALE-TROL Sticky Shale Can't StopYou Anymore," DF-5-75-1M.

12. Chemergy Corporation, "Maintain Maximum Production With PermaFIX andPermaFLO Treatments for CLAY/FINE and SAND CONTROL."

13. ENCYCLOPEDIA POLYMER SCIENCE AND TECHNOLOGY, Suppl. No. 1,"Alkylenimine Polymers," Interscience Publ., N.Y. Copyrighted 1976,pp25-52.

14. Roberts, John D. & Caserio, Marjorie, C., BASIC PRINCIPLES OFORGANIC CHEMISTRY, Pub. W. A. Benjamin Inc., New York, 1965.

15. Mettzer, Yale L.; WATER SOLUBLE RESINS AND POLYMERS, Noyes DataCorp., Park Ridge, N.J., 1976

16. Whistler Roy L.; INDUSTRIAL GUMS, Academic Press, N.Y., 1973.

17. Hoover, Fred M.; "Cationic Quaternary Polyelectrolytes--A LiteratureReview," J. MACROMOL. SCI-CHEM., A4(6), October, 1970, pp 1327-1418.

18. Robinson and Stokes, "Electrolyte Solutions," Butterworth ScientificPublications, 1959.

19. "Enhanced Oil and Gas Recovery & Improved Drilling Methods," 4thAnnual DOE Sumposium Vol. 1A (Oil) of Proceedings, Aug. 29-31, 1978; ppB-1/1-B-1/25; Tulsa, Okla.; Published by The Petroleum Publishing Co.,Box 1260, Tulsa, OK 74104.

In addition to the above references, a presently copending patentapplication in the name of Homer C. McLaughlin and Jimmie D. Weaver,Ser. No. 901,664 filed May 4, 1978, now U.S. Pat. No. 4,462,718,describes the use of various polymers for stabilizing clays in earthenformations, especially a subterranean formation. The above referencesand each reference cited herein are incorporated herein by reference toany extent necessary.

By this invention there is provided a method for altering the propertiesof aqueous or organic fluids or combinations thereof. "Aqueous fluids"as used herein means any fluid containing some water. It can alsocontain other components such as hydrocarbons (such as alcohols, ethersand other miscible or partially miscible solvents), acids, water solubleor water dispersible salts, easily gasifiable components (such as CO₂and N₂) or solids (such as sand, Portland cement and proppants), orother plastics or polymers such as resins. These materials can includethose which are settable to a rigid or semirigid solid as well as thosewhich are not settable. The fluid can also contain particulate materialsuch as sand, clay or acid soluble particles (e.g. carbonate). Thesefluid properties are primarily viscosity and the resulting apparentviscosity of the fluid in various media. This alteration of fluidproperties is useful for producing viscosified and gelled fluids and fortreating various substrates to alter the characteristics of thesubstrate such as its surface active nature or the interaction between atreated substrate and various fluids. The compositions provided by thisinvention for altering fluid properties or treating various substratescan be formulated to produce the combination of composition propertiesdesired, e.g., solubility, affinity or repulsion for various fluidsand/or solids; stability to or degradation by components such as oxygen,acids and water at various temperatures; or viscosity characteristicswhich vary with time, temperature, concentration, etc. Thesecompositions and processes have particular applications in thickeningvarious fluids such as aqueous fluids and acids for treating earthenformations especially those intersected by a well such as those used toproduce water, oil, gas, steam and other resources. The compositions useas an essential component one certain type of polymer. This type ofpolymer is a branched organic polymer having a backbone chain with anaverage of at least one branch chain per backbone chain and with saidbranch chain being an average of at least two polymeric units in length.In the branched polymer up to about 98 per 100 backbone polymer unitscan have one or more branches. The branched polymer can have one or morebranch chains on each polymer unit in the backbone chain if thepolymerization or grafting conditions, polymer units, economics and thelike permit. A polymer unit as used herein refers to the part of apolymer chain derived from a monomer whether in the backbone chain,branch chain or both and whether derived directly from a monomer orwhether partially polymerized or reacted to form a polymer precursor,oligomer or polymer chain.

A preferred class of polymers within the broad class of branchedpolymers of this invention is branched water soluble polymers. Thebranched polymers can contain polymer units, segments or portions invarious arrangements which are oleophilic, oleophobic, hydrophilic,hydrophobic or combinations thereof. One preferred class of branchedpolymers contains large portions, concentrations or proportions ofhydrophilic units or segments. The branched polymers of this inventiongenerally comprise combinations of hydrocarbon radicals and heterogroups. Hydrocarbon radicals as used herein, generally represented by R,contain hydrogen and carbon and can also contain hetero atoms or groupsbut generally hydrogen and carbon are the predominate number of atoms.For example, the hydrocarbon radical can include but is not limited to##STR1##

Another preferred class of branched polymers of this invention are thosecontaining ionic groups. These ionic groups can be cationic, anionic,amphoteric, neutral or ionically balanced or combinations thereof. Theionic groups usually are or contain hetero atoms or groups which as usedherein are oxygen, nitrogen, sulfur, phosphorous, metals such as thealkali metals, alkaline earth metals, Groups IV, V and VII metals of thePeriodic Table, combinations thereof and combinations thereof withcarbon and/or hydrogen. Ionic groups can be included in or with aromaticgroups, heterocyclic groups, unsaturated linkage, carboxyl, carbonyl,keto, amide, imide, sulfo, hydroxyl and such like.

Thus, the invention can be broadly considered as the use of certaintypes of branched polymers and the discovery of certain branchedpolymers which have unexpected stability and effectiveness. For example,in treating an earthen formation or altering properties of an aqueousfluid using a water dispersible polymer, the treatment or alteration canbe improved by using one of these certain branched polymers having amolecular weight of about 900-50,000,000 with an average of at least onebranch chain per backbone chain and with the branch chain being anaverage of at least two polymeric units in length. The branched polymercan optionally be ionic or contain ionic and/or nonionic segmentsdepending on the particular effect and application desired. The branchedpolymer can be made by any one of several methods or variations and canbe made to contain the particular combination of segments and propertiesdesired in view of the teachings herein. Likewise, the branched polymercan be applied or used using any one of numerous methods or variationsthereof.

In one aspect of the invention, branched ionic polymers are used totreat particulate or fibrous formations, especially earthen particles,to alter the fluid flow characteristics and/or surface characteristicsof the particles or earthen formation. The branched polymers of thisinvention can be used to alter the viscosity or gel structure of manyaqueous fluids and to alter the surface properties, fluid flow, andattraction/repulsion characteristics of many formations. The same ordifferent mechanisms may bring about the alterations in the differentapplications. The formations can be composed of loose or consolidatedparticles or fibers. The formation can also be suspended particles,fibers or masses. A formation can be a solid impermeable mass which hasbeen etched or leached to form a porous, permeable formation which isequivalent to a porous permeable formation made by compacting particlesor fibers. Compacted formations can be loose or consolidated by naturalor artificial binders such as resins, inorganic cements, includingsilicate and Portland types. As used herein, particulate and particulateformation shall include each of the above types of particles, formationsor structures. The fluid flow or surface characteristics mean the netresponse of the particles or formation to flow or resistance to flowrelative to a particular fluid and to the attraction, repulsion orrelatively inert nature of the particles or formation to one or morefluids or materials suspended in the fluids. The particles can besuspended in a fluid or packed either loosely or tightly into a mass.Within this aspect of the invention, one particular process involves thetreatment of particles packed into a formation to decrease thepermeability of the formation to the flow of water or an aqueous fluid.The process comprises merely placing or contacting a liquid phaseadjacent to the formation containing an effective amount of a polymer totreat at least a portion of the adjacent formation. The treated zoneshould preferably have a minimum thickness of about one inch. Of course,for applications altering aqueous fluid properties, such as alteringfluid loss of a treatment or drilling fluids, the penetration of aqueousfluid and branched polymer should be a minimum or only a fraction of aninch. The polymer is preferably a branched organic polymer having amolecular weight of about 900-50,000,000 with a backbone chain havingreactive sites on which a branch chain can be or has been attached withbranched chains being attached to the backbone chain in a concentrationof about 0.1-99% of said reactive sites. The branched organic polymeralso contains a hydrophilic portion in a concentration sufficient toproduce the desired hydrophilic-hydrophobic balance within the formationand to alter the hydrophilic characteristics in the formation. Thisliquid phase flows or is pumped or injected into the formation and thepolymer is allowed to contact the formation. For this use, the preferredclasses of polymers have bonding groups, e.g., ionic groups for bondingor attaching to the formation. For example, where the formationpossesses a generally anionic nature, a preferred polymer would be acationic polymer so that the cationic groups can attach or associatewith the anionic sites of the formation. The higher molecular weightpolymers and polymers with high concentrations of ionic groups also tendto make the treatment more permanent and to have improved efficiency oreffectiveness.

In yet another aspect of the invention, another class of polymers can beprepared which have some hydrophobic and/or oleophilic portions,branches or overall nature so that these polymers can be attached toformations or suspended within fluids in the formation to produce asurface effect on the particles or formation which retards the flow oforganic fluids or hydrocarbon fluids and increases the permeability ofthe formation to aqueous fluids or would tend to gel hydrocarbon ororganic based fluids. As used herein, hydrocarbon fluids include bothoil, gas and mixtures thereof. One aspect of altering the permeabilityof the formation is the change of water-oil ratio (WOR). As used hereinWOR shall include the ratio of aqueous fluid to hydrocarbons includingoil, gas or mixtures thereof. The production of various polymer classesto accomplish the desired modification; produce the desired attracting,repelling or suspending properties; and produce the desiredviscosifying, gelling or preference for organic or aqueous liquids canbe prepared in view of the disclosure herein.

For example, a preferred class of cationic polymers which arehydrophilic and have highly hydrophilic branch chains can be used totreat or attach to a formation having anionic sites. This attachment islong lasting or essentially permanent in that the effect is not readilyremoved by washing or flowing through the formation with acids, bases,organic or aqueous fluids. These polymers are also useful for claystabilization. The hydrophilic portion of the polymer hydrates in thepresence of water, brine or most aqueous fluids which is thought toinduce pseudostructure in the aqueous fluid resulting in an apparentincrease in viscosity. Or in other words, the net effect is to increasethe resistance to flow or pressure required to produce a given flow ofaqueous fluid. The hydrophilic portion is thought to partiallydehydrate, shrink or form a smoother flow channel in the presence ofhydrocarbons or other organic fluids, thereby increasing permeability toorganic fluids or not substantially changing the permeability tohydrocarbons. Certain preferred polymers of this invention have aneffectiveness such that they produce at least a 10% change in therelative permeability to an aqueous fluid in most loose or consolidatedparticulate formations, either packs or cores. This hydrophilic natureof the branched polymer also produces an aqueous gelling agent with anunexpectedly high efficiency and high stability even in aqueous andespecially acidic fluids. The effectiveness in gelling an aqueous fluidis indicated by a significant increase in viscosity such as at least a10% increase when compared to similar polymers which are linear.

In addition, certain preferred classes of polymers have long termstability which means this effect will last even after 1000 pore volumesof a normally detrimental fluid has been flowed through the treatedformation. This stability will be affected by the nature of the polymerand particular formation being treated. For example, in siliceous oranionic formations a cationic polymer is preferred and for cationic orneutral formations such as limestone or dolomite, an anionic oramphoteric polymer is preferred. For formations and/or which do not havea clear ionic character or where the ionic nature is weak, the stabilityor longevity can oten be improved by increasing the molecular weight ofthe polymer (e.g. crosslinking) and/or the length and number of branchchains.

Another preferred class of polymers has essentially a neutral, nonionicor amphoteric nature so that it is preferably weakly adsorbed on thehost formation and/or other solids, e.g. suspended particulate solids.In addition, this polymer can solvate and/or swell with either aqueousor organic fluids depending on the exact hydrophilic-hydrophobic natureof the polymer to produce the desired resistance to flow. These polymerscan be used for acidizing, fracturing, gravel or sand packing, shuttingoff fluids flowing in a formation, diverting fluids, drilling, wellcompletion, grouting, flooding or tertiary recovery, or a combinationthereof. They are especially useful for mobility control such as inpolymer flooding and other enhanced recovery methods.

Specific uses of preferred classes of branched polymers include (1)water to oil ratio reduction (i.e., WOR) for wells, (2) reducing waterflow, (3) enhancing the flow or production of hydrocarbons includingoil, gas or mixtures thereof, either singly or in the presence of anaqueous fluid, (4) plugging off or diverting aqueous fluid flow in orinto portions of a formation, (5) increasing viscosity and/or fluid losscontrol of fluids used in a well such as in carrier or treating fluids,gravel packing fluids, drilling, workover or completion fluids, (6)diverting flow of well or formation fluids, e.g., to alter mobility orinjection profile or to control fluid injection, (7) reducing orincreasing resistance to flow of aqueous fluids organic fluids, mixturesthereof or a component thereof in a formation, (8) increasing theviscosity of aqueous or organic fluids and especially as those fluidsenter or encounter certain types of formations, (9) repelling certainfluids, salts, solids or materials of a formation or structure, orsuspended in a fluid, (10) gelling aqueous fluids especially acidicfluids, (11) as carrier fluids for particulate solids, e.g., gravelpacking, fracturing, acidizing, or a combination thereof, (12) claystabilization, (13) as a flocculant for suspended particles, (14)treating surfaces to make them attract or repel aqueous or organicfluids or ionic materials, (15) as an acid extender or retarder, (16)fluid loss control and/or viscosifier for fracturing and/or acidizing,(17) preventing or breaking certain emulsions, especially water andhydrocarbon emulsions commonly encountered in formations, (18) formingan aqueous grouting gel around conduits such as pipelines, wells,tunnels, mine shafts, sewers, hydrocarbon storage caverns, (19) actingas a surfactant or bonding agent between solids and fluids; one or morefluid phases such as for increasing adhesion of resins or consolidatingmaterials to certain surfaces; or one or more solid phases such asbetween solids suspended in a fluid and a formation, and (20) treatmentof uncoated or poorly coated silica surfaces within a resinconsolidation of solids (e.g. gravel packs, formation particulates andthe like) to make resultant consolidation more resistant to waterdeterioration.

Thus, broadly speaking, one preferred application of this inventioncomprises one or more processes and polymer compositions for alteringthe surface characteristics of and/or fluid flow characteristics or asubstrate or a formation which includes contacting said formation with ahighly branched organic polymer which has an attaching portion and amodifying portion. The attaching portion of said polymer generally hasionic groups which establish the desired ionic bond or repulsion in theformation. The modifying portion of said polymer has thehydrophilic-hydrophobic balance desired to produce the desired formationsurface characteristics and/or interaction with fluids such as gellingand increasing or decreasing permeability to certain fluids.

Preferred polymers can be classified according to the majorcharacteristics of the formation to be treated or application, the typeof polymer attaching or adsorption mechanism, the type of modifyingpolymer portion, polymer solubility or suspending characteristics andthe functions which the polymer can perform as shown in the followingtable.

    __________________________________________________________________________    Characteristics Of Branched Polymers                                          Polymer                                                                       Attaching Portion                                                                           Modifying Portion     Formation    Function                            Strength of                                                                          Hydrophilic/                                                                         Ionic                                                                              Solubility Nature                                                                             Major Ionic                         Ionic Nature                                                                         Adsorption                                                                           Hydrophobic                                                                          Nature                                                                             of Polymer                                                                              Type  Nature                              __________________________________________________________________________    Cationic                                                                             Strong Hydrophilic                                                                          Ionic or                                                                           Aqueous fluids                                                                          Sandstone                                                                           Anionic                                                                              Decreasing water perme-                           nonionic                                                                           and/or polar           ability, increasing oil                                solvents               flow or increasing                                                            aqueous                                                                       fluid viscosity.             Anionic or                                                                           Moderate                                                                             Hydrophilic                                                                          Ionic or                                                                           Aqueous fluids                                                                          Limestone                                                                           Cationic                                                                             Decreasing water perme-      Amphoteric           nonionic                                                                           and/or polar           ability, increasing oil                                solvents               flow or increasing                                                            aqueous                                                                       fluid viscosity.             Cationic                                                                             Strong Hydrophobic                                                                          Nonionic                                                                           Organic   Sandstone                                                                           Anionic                                                                              Increasing water perme-                                solvents               ability or increasing                                                         or-                                                                           ganic fluid viscosity.       Anionic or                                                                           Moderate                                                                             Hydrophobic                                                                          Nonionic                                                                           Organic   Limestone                                                                           Cationic                                                                             Increasing water perme-      Amphoteric                solvents               ability or increasing                                                         or-                                                                           ganic fluid viscosity.       Nonionic                                                                             Weak or                                                                              Hydrophilic                                                                          Nonionic                                                                           Aqueous fluids                                                                          Sandstone    Increasing aqueous                                                            fluid                               None               and/or polar                                                                            or           viscosity or diverting                                 solvents  Limestone    aqueous fluid                __________________________________________________________________________                                                     flow.                    

In one preferred embodiment of this invention there is provided a simpleone-stage, one phase, or one-agent treatment process for modifying thesurface characteristics, wettability or fluid flow characteristics of anearthen formation especially a subterranean formation intersected by awell such as a producing oil or gas well. The treatment can also beapplied by grafting or forming the branched polymer in situ. Thistreatment is essentially permanent and highly stable to acids, oxygenand temperatures up to at least 200°-350° F. For some preferred polymerseven higher temperatures can be tolerated. Furthermore, the treatment isvery stable in the presence of most electrolyte solutions such as saltor brine which normally affect other polymers (e.g., polyacrylamides andderivatives) previously used for such treatments. These acrylamidepolymers tend to desorb or break down in the formation. In thistreatment process, a certain class of branched organic polymers having amolecular weight in the range of about 900-50,000,000 are contacted orapplied in a fluid carrier media, preferably an aqueous liquid phase, tothe formation. The polymer carrier fluid can also be an emulsion,aqueous solution of inorganic salts, a hydrocarbon fluid, polar solventsuch as polar and/or oxygenated hydrocarbons or mixtures thereof. Thepolymer has certain ionic and hydrophilic properties. Depending on thesurface properties or wettability characteristics desired for thetreated earthen or particulate formation, the polymer can be nonionic,amphoteric, neutral, anionic, cationic or a combination thereof. Fortreating most sandstone formations and especially subterranean oilproducing formations, the cationic polymer is preferred. For someformations such as those having a high concentration of carbonate, theanionic polymer or amphoteric polymer is preferred. Where weak orreversible adsorbtion is preferred, nonionic polymers can be used suchas for polymer flooding or in tertiary flooding to change the mobilityratio of fluid phases in the formation. The ionic polymer preferably hasa calculated ionic concentration of about 5×10⁻² -1×10⁻¹⁰ or preferably5×10⁻² -1×10⁻⁵ ionic sites per gram atom weight.

The ionic concentration of certain preferred polymers is calculated byadding the number of charges in the form of ionically charged atoms,radicals or groups including both the backbone chain, pendent groups andbranch chain and then dividing that number of charges by the gram atomor molecular weight of the repeating polymer unit or representativeportion of the polymer. This gives the number of charges perrepresentative weight unit of the polymer. For example,polyethyleneamine with one nitrogen per each repeating polymer unit,e.g. ##STR2## has one positively charged nitrogen or cation perrepeating unit and a molecular weight of 44 which gives a charge densityof 1/44 or about 2.3×10⁻². This does not include the counter ion (A⁻).For polymers such as polyalkylamines the ionic charge or degree ofionization can be varied or changed by adjusting the pH, solvent orsalts in the solvent. For ionic concentration calculation purposes, allatoms, radicals or groups which normally can be charged under somecondition of use should be considered charged for the calculation unlessadjustments to ionize some groups would deionize or interfere withothers.

In another example of calculating charge density for a branchedcopolymer of units A, B and C, such as:

    __________________________________________________________________________     ##STR3##                                                                 

    __________________________________________________________________________    CALCULATION OF GRAM ATOM OR MOLECULAR WEIGHT                                  Polymer Unit                                                                         Molecular Wt of Unit                                                                     Number of Units                                                                        Weight of Units in Polymer                         __________________________________________________________________________    A      114        1000     114,000                                            B       58        1000      58,000                                            C      5263        10       52,630                                                                       224,630                                                                       average gram atoms or                                                         molecular weight.                                  __________________________________________________________________________    CALCULATION OF NUMBER OF CHARGES PER UNIT                                     Polymer Unit                                                                          Charges Per Unit                                                                         Number of Units                                                                        Number of Charges                                 __________________________________________________________________________    A       2          1000     2,000                                             B       0          1000        0                                              C       1           10        10                                                                          2,010                                                                         Total Average                                                                 Number of Charges                                 __________________________________________________________________________     Average charge concentration = 2010                                           weight = 8.9 × 10.sup.-3 charges per gram atom weight.             

One preferred type of branched polymer has a substantially linearbackbone having reactive sites on which branched chains can be attached.This substantially linear backbone can be a homopolymer or a copolymerwith the reactive sites in the backbone chain or pendent groups.Substantially linear as used herein includes polymers having pendentgroups which are not more than about two polymer units in length. Themonomer units for this backbone chain can be or contain aliphatic,aromatic, hetero groups, or combinations thereof. As used herein"homopolymer" means a polymer prepared by using monomers with aconcentration of at least about 98% of one type of monomer, andcopolymer covers polymers prepared using more than one type of monomerin concentrations of at least about 1%, i.e., significant portions. Theterm copolymer as used herein includes copolymers, terpolymers, etc.,having 2-8 types of monomers in various concentrations or homopolymerswhere some monomeric units or polymer units have been derivatized suchas hydrolyzed acrylamide. Both homopolymers and copolymers or portionsthereof can be prepared in a one-step regular or a random polymerizationof monomers, oligomers, polymers, or mixtures thereof or by multi-steppolymerization of monomers, oligomers, prepolymers or mixtures thereof.The branched polymer can include randomly polymerized portions,regularly polymerized portions, block polymerized portions orcombinations thereof. The branched polymer or portions thereof can beprepared by any one or more conventional batch or continuouspolymerization processes or it can be polymerized in situ such as in anearthen formation where it is to be applied or used. The effectivenessof the branched polymer for a specific use, its structure and viscosity,the degree of branching, length of polymer chains and such are sensitiveto polymerization conditions and the closeness of control of factorssuch as temperature, diluents or solvents, pressure, pH, electrolytetype and concentration, agitation, and other normal variables. Eachbranch chain can be substantially linear, highly branched itself or withthe degree of branching desired as taught herein.

The stability of the branched polymer is a function of the polymerlinkages and the environment to which they are exposed. The polymershould be stable to exposure to high temperature, acid, oxidation,hydrolysis and shear. For WOR applications high stability is desired.For other applications such as gelling acids the polymer need not be asstable over long periods of time. Preferred backbone linkages includeC--C, C--N--C, C--O--C and combinations thereof. The stability of thebranch chain and pendent group linkages is also critical and should havehigh stability for most applications. For altering fluid flow propertiesin formations, certain preferred branched polymers contain polyamine andpolyether linkages in the branches. It is thought that the branchingalso increases the backbone stability of certain polymers such as thosecontaining ester linkages. Certain preferred polymers having C--Clinkage, ester linkage, and polyether branches have remainedsurprisingly effective at temperatures over about 177° C. This producesa high stability preferred polymer. With the carbon-to-carbon linkage,the ionic groups and hydrophilic or water solubilizing groups are inpendent groups or branch chains. For adequate water solubility thereshould be at least one ionic or hydrophilic group for about each five orsix carbon atoms. That is, the carbon-to-hetero atom or group ratioshould be less than about 7:1. The nature of the ionic or hydrophilicgroups and type of carbon or hydrocarbon groups present will affect thesolubility and ratio of carbon to hydrophilic groups. A preferred classof polymers is water soluble polymers; however, all polymers need not bewater soluble depending upon their use or function. "Water solubility"as used herein means having a solubility of at least five parts permillion (ppm), preferably about 1% by weight, in an aqueous fluid. Forpolymers to be ionically attached to a charged formation or structurebeing treated, the polymer must be at least dispersible in a fluid andat least partially ionizable in the presence of a solvent such as water,a polar solvent or mixtures thereof. It may be desirable to usehydrocarbon liquids, substituted or polar hydrocarbons such asoxygenated hydrocarbons. These hydrocarbon solvents include alcohols(methanol, ethanol, isopropanol), glycol ethers and ethylene glycol andthe like. Easily gasified carrier fluids useful herein include but arenot limited to carbon dioxide, ammonia, nitrogen, low molecular weighthydrocarbons or substituted hydrocarbons. These materials can also beused as an easily gasified component of a liquid system or as aprinciple component of a mist or foam carrier. These fluids can be usedas solvents, carrier fluids, preflushes, afterflushes or a combinationthereof to place or suspend the polymer. The degree of branching,crosslinking, molecular weight and stereo configuration must also beconsidered along with the chemical constituents, e.g. hydrophilic groupsand ionic nature, to determine the solubility, attraction, repulsion,suspension, adsorption and other properties which determine the strengthof attachment to the formation or suspension in a fluid, as well as thefluid properties including adsorption, hydration and resistance to orpromotion of fluid flow for either aqueous or organic fluids. For someapplications it may be desirable to have a polymer or portions thereofthat repels, suspends or disperses solids, the surrounding formationand/or other polymer chains. A high molecular weight polymer with a highconcentration of hydrocarbon groups would tend to produce a highviscosity fluid and be less soluble in aqueous fluid. This polymer couldalso be soluble or dispersible in organic fluids. A high concentrationof hydrophilic groups would tend to increase water solubility, hydrationor solvation. It is believed that for a certain molecular weight, ahighly branched hydrophilic polymer would tend to capture or influencemore water than a more linear hydrophilic polymer and it would moreeffectively hydrate or swell to increase the viscosity of an aqueousfluid in which it was dissolve or with which it became associated whileattached to a formation or structure. That is, the random branchedpolymer would have a larger hydrodynamic volume or associate with morewater and be more effective to reduce aqueous fluid flow. However, apolymer with longer hydrophilic branches would be more effective forgelling aqueous fluids or reducing WOR than one with shorter branches,especially in high permeability formations or those having larger pores.

For high aqueous fluid solubility polymers or those with high ionicconcentration, it is desirable to have hetero atoms or groups such asnitrogen, oxygen, phosphorous, sulfur, carboxyl, carbonyl, carbinol,cyano, ether, acetal, carboxyamide, alkylidene, alkylene, or substitutedaromatic groups in the branched polymer. The first eleven atoms andgroups are preferred. The hetero groups and branch chains should beselected for the stability desired. They can also be arranged todecrease stability of the polymer for some applications such as byhydrolysis, attack by acid or oxygen, or thermal decomposition.

In one method of preparing the branched polymer, the backbone chain mustcontain reactive sites which will react with a corresponding reactivesite in the monomer or in the branch chain to be attached. The branchingcan also be accomplished by homopolymerization where the monomer reactswith other monomers, oligomers or polymers to randomly form branches ora branched polymer as in the case of certain alkyleneimines (e.g. anaziridene to produce PEI) in which the alkylene group preferablycontains about 2-3 carbon atoms. In another method, the branch chain canbe attached to a monomer unit and then one type or a mixture of monomersare polymerized to form the backbone chain, branch chain or both. Thebranching can also be accomplished by reacting with or grafting a branchpolymer chain onto a linear backbone chain, a slightly branched backbonechain or a backbone chain having pendent groups. The branch chain can beattached through corresponding reactive sites to the linear backbonechain or to what might be considered a pendent branch or a pendent groupof the branch chain. After the branch chain or branch chain monomers areattached, the reactive site can be considered no longer reactive. Aswith the backbone chain the branch chain or pendent groups can contain,but are not limited to, hereto atoms or groups such as oxygen, nitrogen,phosphorus, halides, hydroxyl, carbinol, acetal, hydroxy, alkoxy,alkepoxy, carboxyl, ester, keto, cationic salt, amide, amine, imide,imine, other nitrogen groups, similar sulfur groups, unsaturated andcyclic carbon-to-carbon or carbon-to-hetero atom linkages. The term"hetero" also includes metals such as the alkali metals (Group IA),alkaline earth metals (Group IIA) and metals of Group III, IV, V andVIII of the Periodic Table such as lithium, sodium, potassium, copper,rubidium, silver, cesium, magnesium, calcium, zinc, strontium, cadmium,barium, aluminum, titanium, zirconium, cerium, molybdenum, lead,vanidium, arsenic, antimony, bismuth, chromium, tungsten, manganese,iron, cobalt, nickel, and combinations thereof. The branched polymer canalso be made by reacting or polymerizing one or more monomers ontoreactive sites in or on the backbone chain to produce random lengthbranches at various locations on the backbone polymer and/or on variousbranch chains.

In one method the reactive sites in the polymer backbone chain, branchchain or monomer can be any atom, radical or group which will react witha corresponding reactive group in the backbone chain, branch chain ormonomer to attach the branch chain to the backbone chain. In forming,branching or grafting the polymer, there must be at least one reactivesite in the backbone chain to attach a branch chain but there may be oneor more reactive sites in the branch chain as long as crosslinking isnot a significant problem. The reactive site or sites can be considereda branching agent. The branching agent can also be a complete monomericor polymeric unit having one or more reactive sites which will react orpolymerize to form the branched polymer of this invention or a portionthereof. Especially for in situ grafting or polymerization, thebranching agent would be considered a monomer, oligomer or polymer andnot merely the reactive site or group such as epichlorohydrin attachedto the branching or crosslinking polymer. Some crosslinking can betolerated and in special cases such as low ionic attraction, highformation porosity, and high temperature environment, extensivecrosslinking along with the branching is helpful for stability andeffectiveness, especially for WOR reduction, grouting, diverting flow,etc. The resulting polymer should still be water soluble.

The reactive sites can be selected from one or more of the followingchemical groups to react with a corresponding reactive site: (1)alcohol, (2) aldehyde or ketone, (3) alkene, (4) alkyl halide, (5)alkyne, (6) amine, (7) an acid or acid equivalent including an ester,anhydride or an acyl halide, (8) amide, (9) epoxide, (10) acetal orketal, (11) nitrile, (12) sulfides and similar or equivalent reactivegroups.

It is recognized that the effectiveness of branched polymers in reducingwater flow and/or altering aqueous fluid properties appears to encompassseveral molecular variables. Particular characteristics may beconstructed into the branched polymers to satisfy different applicationssuch as degree of branching, length of branches, ionic nature ofbackbone and branches, molecular weight of backbone and branching, anddegree of crosslinking.

For attaching the polymer to particulate solids, generally it ispreferred that the predominant ionic charge on the surfaces of asubstrate or solids be reacted with a branched polymer which possessesopposite ionic charges in the backbone structure; however, workabilityis not limited to this mechanism. Higher molecular weight branchedpolymers also tend to adhere to surfaces which can possess the samepredominant surface charge as the polymer. Some degree of crosslinkingof the branched polymers also tend to increase this molecular weight andimpart this improved property. The mechanism(s) involved in coatingthese surfaces is not fully understood.

Greater efficiency in reducing water permeability is related to a higherdegree of branching and with the higher molecular weight hydrophilicbranches and backbone structure. Some crosslinking can be advantageoussince the molecular structure is enlarged. However, sufficient openended branches are necessary to effect the reduction in water productionand/or mobility.

For attaching to predominantly anionic sandstone (silica) formations,certain preferred polymeric structures should contain sufficientcationic (+) sites to cause strong attraction of the polymer tosandstone surfaces or other particulated solids (anionic surfaceproperties). These strongly cationic polymers also will stabilize claysand fines within a surface or subterranean structure while impartingdesirable properties (aforedescribed) in the formation or particulatedsolids. These polymers stabilize sensitive formations such as thosecontaining clay so that they are less sensitive to swelling, dispersion,erosion or other damage from fluids such as hydrocarbon fluids(especially gas), aqueous fluids or other formation fluids which canresult in migration, plugging or other types of damage which reducepermeability. These polymers also increase the stability of a resinconsolidated formation. These polymers can also modify the surfacecharacteristics of particles such as sand, silica flour, asbestos andthe like.

In another situation it is desired that predominately cationicparticulated solids composed of calcareous components (cationic (+)surfaces) e.g., CaCO₃, CaMg(CO₃)₂ (dolomite), FeCO₃ (siderite, etc.) betreated with polymers containing a sufficient quantity of anionic (-)sites to result in strong attraction of the polymer to the solids.Limestone formations represent the above described calcareousstructures.

Formations often contain particulated solids of varying or mixedcompositions and ionic surface properties. The formations may be treatedseparately with two or more polymeric types; for example, one treatmentmay involve a cationic (+) polymeric structure to promote attraction tothe anionic (-) (sand, clays, silica, etc.) surfaces. A simultaneoussubsequent treatment with a polymer containing anionic sites can be usedto cause strong attraction to the cationic surfaces. The above exampledescribes one method of treating a formation of differing ionicsurfaces. Branched polymers with different ionic groups or mixtures ofdifferent ionic properties can also be used on formation with onepredominant ionic character. Alternately, a polymer of this inventionmay contain anionic, cationic or other types of ionic groups, portionsor segments so that formations of mixed compositions or severalformations of varying nature can be treated with one type of polymericmaterial in one or more steps or applications. However, the scope ofthis invention is to include other procedures and modifications whichrepresent the basic concept as taught.

For some applications, it is desired that the polymeric molecules becharacterized by little or no chemical crosslinking of polymericsegments. Some crosslinking may be desired in other areas. The polymersmust possess sufficient hydrophilic properties to cause some thickeningof aqueous fluids. Generally, for a given branched polymer family it hasbeen observed that polymers having higher viscosity are more effectivethan those of the same family having lower viscosity at the sameconcentration.

For certain preferred polymers, the backbone, if definable, may belinear, branched, irregular shaped, or otherwise and can be composed ofa homopolymer or copolymer structure. Sufficient reactive sites must beavailable on the backbone for chemically attaching desirable polymericchains. Side chains may also be represented by a homopolymer orcopolymer structures and may take on a linear, branched, irregularshaped or other type configuration. The branch chain can also beattached to pendent groups of a polymeric backbone. The resultingpolymeric structure must contain the necessary ionic charges,flexibility and balance to facilitate strong and long lasting ionicbonding between it and the particulated solids. It should provideadequate hydrophilic (water loving) segments of sufficient ionic natureto cause significantly effective resistance to the flow of aqueousfluids through porous media while causing little or no resistance toflow of hydrocarbons therethrough. The polymeric material may alsoimpart long lasting surface properties to the particulated solids suchas causing enhancement of oil flow by increasing the oil permeability.Polymeric structures should possess the following additional properties.The ionic characteristic of the polymer may be one or more types, e.g.,a polymeric molecule may possess only cationic properties whereasanother polymeric structure may contain nonionic, cationic, anionic,neutral, amphoteric segments or combinations thereof. Ionic interferenceor interaction within the polymer or between polymers may cause problemswith different types of ionic segments.

For one preferred class of highly branched, water soluble cationicpolymers, the backbone will contain the cationic groups or radicals andthe branched chains can contain additional groups, amphoteric groups,nonionic groups and/or be a neutral group. For substantially linearbackbone chains, the molecular weight of the backbone should be in therange of about 1000-5,000,000.

The polymer unit of the branch chains can be one or more of the polymerunits given for the polymer backbone chain. As indicated above thebranch chains can contain the same polymer units for randomlypolymerized homo or copolymers. For randomly polymerized backbone chain,branch chain or both, the polymer chain can be selected arbitrarily sothat even the branch chains would have branches. For graftpolymerization or separately attaching the branch chain to a backbonechain, the branch chain can also have several branches attached throughone or more reactive sites. The branch chains can also comprisedifferent random polymer units which can be made up of one type ofrepeating unit or one or more different repeating units. Branch chainscan also be graft polymerized onto the polymer backbone chain as aseparate polymerization step. More than one type or length branch chaincan be grafted to the backbone chain. The branch chain can also beanother homo or copolymer chain containing a reactive site which willattach to a corresponding reactive site in the backbone polymer chain.The molecular weight range of these branch chains can be about100-5,000,000 or preferably about 300-1,000,000 for water soluble WORreduction or aqueous fluid gelling polymers.

The polymer chain can contain hydrophilic or hydrophobic groups,oleophilic or oleophobic groups, hetero groups and/or ionic groupsincluding amphoteric, nonionic. cationic, neutralized or anionic. Eitherthe polymer backbone or branch chain or both can include ionic groups.The number or concentration of each of these groups, their location andthe surrounding media, solvent or fluid will determine the net oroverall properties and effect of the branched organic polymer. Thebranched polymers of this invention can be prepared by conventionalmethods as described in the references cited and incorporated herein.The backbone chain, branch chain or both can be regular homo polymers,random copolymers of two or more monomers, block copolymers, segmentedrandom copolymers or combinations thereof.

The branched polymers of this invention can have a molecular weight inthe range of about 900-50,000,000. The molecular weight is generally notcritical except for a minimum value for each polymer family depending onthe application and other polymer characteristics such as degree ofbranching, ionic nature, degree of crosslinking, as well as theeffectiveness and stability desired. Generally, the higher the molecularweight, the more effective the polymer is for increasing viscosity orreducing permeability to fluid flow. Polymers having a molecular weightnear the lower critical limit for a given application may be effectivefor a short time but are usually less stable to detrimental fluid flowor adverse conditions. A higher degree of branching and/or crosslinkinggenerally makes the lower molecular weight polymers more effective formost applications. Preferred classes of branched polymers have anaverage molecular weight of about 100,000-5,000,000 for mostapplications; higher aqueous viscosities are produced with molecularweights up to about 10,000,000-15,000,000. Polymers having molecularweights of about 10,000-2,000,000 are effective for several uses and areeasier to handle than higher molecular weight polymers. For certainapplications where high viscosity or effectiveness is not critical, orfor less permeable formations, lower molecular weight polymers such asabout 1,000-9,000,000 can be used. Some polymers can also be used andbranched or crosslinked in situ for easier handling and/or greatereffectiveness.

The backbone polymers can have a molecular weight of about 800 to nearly50,000,000; preferably about 1,000-5,000,000 for WOR reduction; andabout 10,000-10,000,000 for use as an aqueous viscosifier or fluid losscontrol agent. These backbone polymers can be used to produce branchedpolymers having a molecular weight of about 9,000-9,000,000; about100,000-20,000,000; or even higher than 50,000,000 depending upon thenumber and size of branch chains attached and the degree ofcrosslinking, if any.

The branch chains can have molecular weights up to about one million oreven higher, generally if the chain is highly hydrophilic and highlybranched itself. One class of preferred branch polymers, beforeattaching to the backbone, have molecular weights of about 300-50,000.For greater WOR effectiveness, higher molecular weight and a higherdegree of branching are preferred, even up to a molecular weight ofabout 100,000 or even about 1,000,000.

With more soluble, more highly branched or compact polymers, highermolecular weight polymers are preferred since they are generally moreeffective and can be acceptably handled. Crosslinking, either in thepreparation or in situ, can in effect increase the branched polymermolecular weight. This crosslinking can occur in batch or continuouspreparation of the branched polymer or in situ when the branched polymeris applied to a formation. The degree of crosslinking will limit thedegree of water solubility or water dispersibility since the polymertends to become less soluble or dispersible and form a more rigid gelstructure with increased crosslinking. The gel structure is desirablefor some applications such as plugging formations or grouting voids orhigh permeability zones around conduits such as wells, caverns, tunnels,pipelines, and the like. The limiting factor on molecular weight of thebackbone polymer, branch chain polymer and/or resulting branched organicpolymer is the maximum fluid viscosity which can be handled in making,mixing and placing the components and/or resulting polymer.

The polymer branched chains can be any polymeric group having thedesired hydrophilic-hydrophobic properties and a reactive group whichwill connect with the reactive sites on the backbone chain. The reactivegroup will preferably be on or near one end of the branch chain but itcan be anywhere in the chain or in a pendent group. For one preferredclass of polymers used to reduce the flow of water through earthenformations or to reduce the production of water in an oil well, thebranched chain and overall polymer should be hydrophilic with thebranched chain having from about 2-50,000 repeating polymer units. Thesebranch chains can be substantially linear or branched themselves. Insome cases multi- or difunctional branched polymers can be used havingterminal reactive groups if one reactive group can be capped orinactivated to prevent or reduce crosslinking. Some crosslinking, forexample about 5%, can be tolerated and is advantageous for certainapplications. Several preferred groups of branched polymer chains arethe polyalkylene imines and polyalkylene oxides in which the alkyleneradicals contain from about 1-3 carbon atoms. Examples of othermonomeric units which can be used to form the branched polymer chainsare acrylamide, acrylate, vinyl alcohol, vinyl ethers, hexoses, allylalcohols, allyl amines, substituted derivatives thereof such assulfonated acrylamide, as well as copolymers and combinations thereof.Generally monomers, polymers and polymer units which can be used for thebackbone chain can be used for the branch chain.

For one type of preferred hydrophilic branched polymers useful forviscosifiers, decreasing WOR or decreasing the flow of aqueous fluidsin, into or within a formation, the predominant ionic groups preferablyin or near the backbone chain will be cationic groups. The preferredpolymer branch repeating units will be --CH₂ --CH₂ --O--, --CH₂ --CH₂--NH--, --CH₂ --CH₂ --N═ or combinations or substituents thereof. Thesepreferred polymer units can be written --R--X-- wherein R is defined asherein and X represents a hetero group such as nitrogen, oxygen, orsulfur having at least two bonds. The R group shown above is C₂ alkylradical ethylene. X can also be another R group, non-existent or withinthe R group. These chains will preferably be monofunctional or morereactive at one end such as being capped or terminated on one end by arelatively nonreactive group and on the other end by a branching agent.These --R--X-- groups can be acrylate, acrylamide, vinyl alcohol, methylvinyl ether, a C₁ -C₆ alkyl, aryl, combinations thereof, or combinationsthereof with hetero groups, especially through a hetero atom as givenabove such as C₁ -C₆ alkyl with hetero groups. Examples of preferredterminal groups are alkoxy (e.g. --OCH₃, --OCH₂ --CH₃); aroxy ##STR4##

Commercially available monomers, equivalents or polymers containing them(either homopolymers or copolymers) which can be used for the branchedpolymers (either in the backbone, branch or both) of this invention areacrylic acid; acrylic esters; methacrylic acid; methacrylate esters;maleic anhydride; itaconic acid; 2-acrylamido-2-methyl propane sulfonicacid; acrylonitrile; sodium vinyl sulfonate; sodium styrene sulfonate;dimethylaminoethyl methacrylate; allyl sulfonate; vinyl acetate;methacryloyloxyethyltrimethyl ammonium methosulfate; alkenes; vinylacetamide; vinyl ethers; vinyl phosphonates; vinyl phosphates; vinylphosphines; diethylaminoethyl acrylate;3-methacryloyloxy-2-hydroxy-propyl trimethylammonium chloride; 4-vinylpyridine; 2-vinyl pyridine; N-methyl-5-methyl-2-vinyl pyridiniummethosulfate; 1,1-dimethyl-1-(2-hydroxypropyl)-amino methacrylamide;dimethyldiallylammonium chloride; diallyl-amine; triallyl amine;methyldiallyl amine; diallyl ammonium salts;betaacryloyloxyethyldimethyl sulfonium methosulfate; ethylene oxide;propylene oxide; N,N-disubstituted methacrylamides; N-substitutedmethacrylamides; methacrylamide; N,N-disubstituted acrylamides;N-substituted acrylamides; N-vinyl pyrrolidone; acrylamide;diacetone-acryl amide; ethyleneimine; propylenimine; ethylene chloridereacted with ammonia; 1-vinyl-2,3-dimethylimidazolinium methylsulfate;N-vinylimidazole; glycidyl alcohol; epichlorohydrin; glycidylmethacrylate; vinyl carbonate; allylglycidyl ether; isoprene andchloroprene.

Conventional methods of polymerization, grafting or branching, andhandling can be used to prepare and apply the polymers of this inventionin view of this disclosure and the references cited herein. Typicalpolymers, polymerization techniques and methods of application aredescribed in the following U.S. patents and other patents cited here:U.S. Pat. No. Re. 29,595 to Adams et al; U.S. Pat. No. 2,223,933 toGarrison; U.S. Pat. No. 2,331,594 to Blair; U.S. Pat. No. 2,345,713 toMoore et al; U.S. Pat. No. 3,500,929 to Eilers et al; U.S. Pat. No.3,822,749 to Thigpen; and U.S. Pat. No. 4,058,491 to Steckler which areincorporated herein by reference to the extent necessary. One preferredmethod for formulating one cationic branched polymer of this inventionis the solvent method using an aqueous media containing a highconcentration of electrolyte such as an alkali metal halide, preferablysodium chloride or potassium chloride. In this preferred method, thereaction conditions, time and agitation should be controlled to producethe branched polymer of the desired molecular weight and structurewithout unduly mechanically shearing the polymer chain or interferingwith the reaction. For higher degrees of agitation the reaction timeshould be lengthened to produce the desired polymer size and structure.The molecular weight, structure and effectiveness of the resultingbranched polymer for a particular use are sensitive to reactionconditions and conditions to which the polymer is exposed, including pH,temperature, pressure, time, contaminants, solvents or diluents,electrolyte, concentration, agitation, and other typical variables.Typical procedures are given in more detail herein as Proceedures. Thereferences previously cited and incorporated by reference also describevarious aqueous and organic solvents and emulsion techniques which canbe used.

The polymers used in this invention can be applied to most particulatesolids or formations by either spraying, pouring or applying the polymerdirectly to the formation or particles. The polymer can be placed in asuitable liquid phase or media adjacent the formation to be treated andallowing, forcing, injecting or pumping the liquid phase into theformation so that the polymer contacts or treats the formation or thedesired portion of the formation to alter the wettability or surfacecharacteristics of the formation as desired. Particulate material (e.g.sand, silica flour and asbestos) can also be added to or suspended inthe polymer or a fluid containing the polymer. For an oil well this canbe simply done by placing an aqueous, organic or mixed liquid phasecontaining the polymer adjacent the formation to be treated anddisplacing or forcing the liquid phase containing the polymer into theformation. The carrier fluid can be one or various mixtures of gas,liquid or solids such as foams, emulsions or slurries. The treatment ofa subterranean formation through an oil well can be accomplished usingone or more liquid spacers, preflushes or afterflushes such as a dilutesalt solution, preferably ammonium halide and/or an aqueous alkali metalhalide solution, into the formation to pretreat or clean the formation,then injecting the liquid phase containing the polymer in aconcentration of up to about 10%, preferably 0.005 to 1.0%, in thequantity calculated to contact the desired portion of the formation withthe liquid phase and highly branched ionic polymer. In some cases apreflush, containing an extending agent such as a surfactant, a nonionicpolymer or an ionic linear polymer which will be adsorbed on theformation, can be used to allow displacement of the branched treatingpolymer away from the well bore or formation surface. This preflush ineffect ties up the ionic sites in the formation and allows the branchedpolymer to pass through this zone with minimal treatment by the branchedpolymer. This zone treated with an extending agent would normally havehigh permeability to water. The branched polymer would then treat theadjacent formation zone. This would leave a zone having highpermeability to water between the branched polymer treated zone and thewell bore. This in effect would increase the effective radius or bore ofthe branched polymer treated zone around the well. The polymer can be ina liquid phase which is aqueous, organic or a substituted hydrocarbonsuch as an alcohol, ester, ether, ketone, aldehyde, amide, or anemulsion or mixture of two or more of these liquid phases with water oranother organic liquid. A foamed carrier can also be used. The carrieror other fluid phases can be acidic, basic or neutral. Acids or acidiccarrier fluids can also be used.

Optionally, the polymer can also be carried in aqueous acid or saltsolutions. A preferred acid carrier can contain up to 37% acid, such asmineral acid, organic acid or mixtures thereof, for example,hydrochloric, hydrofluoric, acetic, fumaric and the like. Otherpreferred acid concentrations are: for fracture acidizing up to about28% or 15-28%; for fracture acidizing with proppant such as sand, 3-5%;and for use with WOR control treatments 0-5%. A preferred aqueous acidiccarrier should have a pH adjusted below about 7 or 6.5 with a suitablemineral or organic acid or equivalent such as hydrofluoric,hydrochloric, nitric, sulfuric, phosphoric, acetic, formic,hydroxyacetic, sulfamic, citric, fumaric, oxalic, and sodium dihydrogenphosphate. Acid producing compounds, equivalents or precursors can alsobe used such as ammonium bifluoride, acetic anhydride, and methylformate. For higher concentrations of certain polymers, high viscosityand pumping pressure may be a problem. The carrier fluid can contain oneor more acids, diluents, solvents or other liquid phases as carrierfluid or injected in sequence with the carrier. When the branchedpolymer is mixed with an acid or acidic fluid the mixture can be usedfor one or more of several functions such as fracturing, acidizing, acidfracturing, or removing unwanted material such as scale, carbonates,rust and other plugging material from wells, tubular goods, a formation,or process equipment. In some cases the branched polymer could befashioned to treat the cleaned surfaces as well as a particulateformation. This branched polymer treatment can also serve to reducedeposition or formation of certain detrimental materials such asparaffin, scale, carbonate, rush and the like. Some branched polymersalso serve to extend or retard the acids or in other words the polymerextends the time required for a given concentration of acid to reactwith a given amount of substrate. This would permit injection of an acidcontaining the polymer deeper into a formation before the acid was spentor would permit a reaction with material deeper in the formation. Thecarrier liquid can also be either a water-in-oil or oil-in-wateremulsion and the carrier fluid may contain optional ingredients such asparticulate material as used in fracturing, surfactants which arecompatible with the polymer, inhibitors and diverting agents. Thepolymers can be applied, mixed with other polymers or additives, so thatmore than one treatment is performed concurrently. Since certainpreferred polymer treatments are substantially permanent and stable tobrine and most acids, these polymer phases can be displaced from thewell bore or displaced within the treated formation using additionalcarrier fluid, acids, aqueous or organic phases. In addition, thetreatment may be conducted in one or more treatment phases with variousspacer fluids or other types of treatment fluids between the liquidphase containing the polymer.

For use in well fluids such as for drilling, completion, testing,cementing or cementing compositions, one preferred carrier is an aqueousfluid. This fluid preferably has a basic pH or a pH greater than about6.5 or 7 and preferably above about 10 or 12. The pH of most Portlandcement compositions is above about 12. In these fluids the branchedpolymer can serve to treat formations contacted by the fluid or to treatthe fluid itself (e.g., reduce fluid loss, increase viscosity of thefluid and gel the fluid).

Polymer units which can be used for the branched polymers of thisinvention can be generally any type of polymer unit that can beconnected to other polymer units of the same or a different type to forma branched water soluble polymer. More particularly, polymer units canbe made or derived from one or more of the classes consisting of (1)vinyl monomers or diene monomers which produce a chain withcarbon-to-carbon linkage which can contain a double bond; (2) diallylicmonomers which can produce a cyclic or hetero cyclic portion in thepolymer chain; (3) imine or amine type monomers which result in nitrogenatoms in the polymer chain; (4) amide type monomers which include nylonand protein type polymer units; (5) saccharide monomer units, polymersof and derivatives thereof which include the starches, guars, xanthangum polymer, cellulose and derivatives thereof; (6) ethers and sulfideswhich include oxygen and sulfur in the polymer chain; (7) carbonateswhich include the carbonate group in the polymer chain such as either ina linear chain or in a pendent group; and (8) urethanes which includethe urethane linkage in the polymer chain either in a linear chain or ina pendent group. These polymer units can be present as a predominantclass or combined in regular, random, block or other variouscombinations. With polymer units which are less soluble than desired ina particular fluid other polymer units, substituents, certain branchchains or a combination of these can be used to produce the desiredsolubility and overall polymer characteristics required for the intendeduse. However, the polymers of this invention include those wherein asignificant portion (at least about 0.1% and preferably 1%) of thebranched polymer units are defined by the above classes or at least oneformula set forth herein. The above polymer units can be represented orillustrated by one or more of the structural formula set forth herein.

Class I: vinyl or diene polymer units can be defined as: ##STR5##

wherein R₁, R₂, R₄, R₇, R₈, R₁₀, R₁₃, R₁₄ and R₁₆ are independentlyhydrogen, alkyl, alkenyl, alkynyl, aryl, acyl, cyclic hydrocarbon,heterocyclic hydrocarbon, hydroxyl, carboxyl, carbonyl, --OR₁₉, --NR₁₉R₂₀, --SR₁₉ R₂₀ ⁺, X_(A), or combinations thereof which also can containoxygen, nitrogen, sulfur or phosphorous;

wherein X_(A) is --Cl, --Br or --NO₂ ;

wherein R₃, R₅, R₆, R₉, R₁₁, R₁₂, R₁₅, R₁₇ and R₁₈ are independentlynon-existent or alkyl, alkenyl, alkynyl, acyl, aryl, carbonyl, carboxyl,aromatic hydrocarbon, cyclic hydrocarbon, heterocyclic hydrocarbon, orcombinations thereof which can also contain oxygen, sulfur, nitrogen orphosphorous;

wherein R₁₉, R₂₀, R₂₁ and R₂₂ are independently non-existent, hydrogen,alkyl, alkenyl, alkynyl, aryl, acyl, cyclic hydrocarbon, heterocyclichydrocarbon, or combinations thereof which can also contain oxygen,sulfur, nitrogen or phosphorous;

wherein R₂₃ is independently in each position hydrogen, alkyl, alkenyl,alkynyl, aryl, acyl, cyclic hydrocarbon, heterocyclic hydrocarbon, M⁺¹,M⁺², M⁺³, M⁺⁴, ⁺ NR₁₉ R₂₀ R₂₁ R₂₂, or combinations thereof which canalso contain oxygen, sulfur, nitrogen or phosphorous;

wherein R₂₄ is independently in each position alkyl, alkenyl, alkynyl,aromatic hydrocarbon, or combinations thereof which can also containoxygen, sulfur, nitrogen or phosphorous wherein R₂₄ has two or moreatoms bonded together with the nitrogen to form a ring;

wherein M is independently in each position ammonium, substitutedammonium, a metal ion or a mixture thereof;

wherein G₁, G₂, and G₃ can be independently non-existent hydrogen,##STR6## or combinations thereof;

wherein n₁, n₂ and n₃ are independently integers of about 0-500,000where n₁ +n₂ +n₃ ≧3;

wherein each hydrocarbon radical independently contains 0-10 carbonatoms and optionally 0-4 hetero groups of oxygen, sulfur, nitrogen orphosphorous; and

wherein the radicals attached to each atom and the structural formulabalance the bonds of that atom.

As used herein, any unspecified bond or radical can be hydrogen, adouble bond, a cyclic bond or where appropriate one of the otherstructures described herein. The radicals or groups having a primenumber designation (e.g., R_(19') ; R_(20') ; etc.) are independentlydefined the same as for the same radical or group with the unprimed basenumber. In view of this disclosure, one skilled in the art will knowwhich radicals, bonds and structures are appropriate or can be possiblefor each combination to form a stable polymer configuration. Forexample, the structural formula of each polymer unit, radical or groupcan have internal atoms or radicals, internal bonds, more than one bondor different types of bonds to balance the bonds of adjacent units,radicals or groups. Stability as used here merely means that thestructure and/or combination is possible or is one definition and notthat the structure must be capable of proof or isolation. Substitutedammonium as used herein is defined as ⁺ NR₁₉ R₂₀ R₂₁ R₂₂. M as usedherein refers to a cation and A refers to an anion whose charge can varyfrom about 1-4.

Class II: diallylic polymer units can be defined as: ##STR7##

wherein R₂₅, R₂₆, R₂₈, R₂₉, R₃₁ and R₃₂ are independently defined as R₁;

wherein R₂₇, R₃₀ and R₃₃ are independently alkyl, alkenyl, alkynyl,aromatic hydrocarbon, or combinations thereof which can also containoxygen, nitrogen, sulfur or phosphorous with each of these R groupsbeing two or more atoms bonded together with G group shown to form aring;

wherein G₄, G₅ and G₆ are independently ##STR8## with R₁₉, R₂₀ and R₂₄are the same as previously defined herein;

wherein n₄, n₅ and n₆ are independently integers of about 0-500,000where n₄ +n₅ +n₆ ≧3; and

wherein the other appropriate conditions of Class I apply to Class IIpolymer units.

Class III: imine or amine type polymer units can be defined as: ##STR9##

wherein R₃₄, R₃₇, R₃₈, R₄₁, R₄₂ and R₄₅ are independently defined as R₃;

wherein R₃₅, R₃₆, R₃₉, R₄₀, R₄₃ and R₄₄ are independently hydrogen,alkyl, alkenyl, alkynyl, aryl, acyl, carboxyl, carbonyl, cyclichydrocarbon, heterocyclic hydrocarbon, --OR₂₃, --NR₁₉ R₂₃, --SR₂₃,--SR₁₉ R₂₃ ⁺, X_(A), or combinations thereof which can also containoxygen, nitrogen, sulfur, or phosphorous with R₁₉ and R₂₃ the same aspreviously defined herein;

wherein n₇, n₈ and n₉ are independently integers of about 0-500,000where n₇ +n₈ +n₉ ≧3; and

wherein the other appropriate conditions of Class I apply to Class IIIpolymer units.

Class IV: amide type polymer units can be defined as: ##STR10##

wherein R₄₆, R₄₇, R₄₉, R₅₀, R₅₂ and R₅₃ are independently defined thesame as R₁ except for --OR₁₉, --NR₁₉ R₂₀, --SR₁₉, --SR₁₉ R₂₀ ⁺, andX_(A) ; and they can be independently non-existent;

wherein R₄₈, R₅₁ and R₅₄ are independently defined the same as R₃,provided however all three R groups cannot be non-existent;

wherein n₁₀, n₁₁ and n₁₂ are independently integers of about 0-500,000where n₁₀ +n₁₁ +n₁₂ ≧3; and

wherein the other appropriate conditions of Class I apply to Class IVpolymer units.

Class V: saccharide and saccharide derivative units can be defined as:##STR11##

wherein R₅₅, R₅₆, R₅₇, R₅₈, R₅₉, R₆₀, R₆₁, R₆₂ and R₆₃ are independentlyhydrogen, alkyl, alkenyl, alkynyl, aryl, acyl, carboxyl, carbonyl,cyclic hydrocarbon, heterocyclic hydrocarbon, M⁺¹, M⁺², M⁺³, M⁺⁴, apentose unit, a hexose unit, --OR₁₉, or combinations thereof which canalso contain oxygen, nitrogen, sulfur or phosphorous;

wherein M is defined the same as previously;

wherein n₁₃, n₁₄ and n₁₅ are independently integers of about 0-500,000with n₁₃ +n₁₄ +n₁₅ ≧3; and

wherein the other appropriate conditions of Class I apply to Class Vpolymer units.

As shown above conventional chemical terminology applies so that carbonatoms are indicated at the intersection of lines of the six-memberedrings except where the oxygen (O) atom is indicated. No specificstereochemistry or stereostructure is meant to be implied by thestructural formula herein. In other words, the structural formula shownis meant to cover all applicable variations and equivalents.

Class VI: ethers and sulfide polymer units can be defined as: ##STR12##

wherein R₆₄, R₆₇ and R₇₀ are independently defined the same as R₃ ;

wherein R₆₅, R₆₆, R₆₈, R₇₁, and R₇₂ are independently defined the sameas R₁ except for hydroxyl;

wherein X_(B), X_(C) and X_(D) are independently oxygen or sulfur;

wherein n₁₆, n₁₇, and n₁₈ are independently integers of about 0-500,000with n₁₆ +n₁₇ +n₁₈ ≧3; and

wherein the other appropriate conditions of Class I apply to the ClassVI polymer units.

Class VII: carbonate polymer units can be defined as: ##STR13##

wherein R₇₃, R₇₄ and R₇₅ are independently defined the same as R₃ ;

wherein n₁₉, n₂₀ and n₂₁ are independently integers of about of0-500,000 with n₁₉ +n₂₀ +n₂₁ ≧3; and

wherein the other appropriate conditions of Class I apply to Class VIIpolymer units.

As shown above the unconnected bonds of the n₂₁ type polymer unit can beconnected to another similar polymer unit or each bond can beindependently connected to another type of radical or polymer unit.

Class VIII: urethane or urea polymer units can be defined as: ##STR14##

wherein R₇₆, R₇₇, R₇₈, R₇₉, R₈₀ and R₈₁ are independently defined thesame as R₃ ;

wherein X₅, X₆, X₇ and X₈ are independently --O--, ═NR₁₉, ═PR₁₉, or--S--;

wherein n₂₂ and n₂₃ are independently integers of about 0-500,000 withn₂₂ +n₂₃ ≧3; and

wherein the other appropriate conditions of Classes I and VII apply tothe polymer units of Class VIII.

The hydrogen attached to nitrogen atoms above can be reacted withanother radical such as a ketone, isocyanate, acid halide, epoxide, andthe like to further branch or crosslink the branched polymer.

Examples of polymer units within Class I are:

A. ##STR15## with

R₁, R₂, R₇, R₈, R₁₃, R₁₄ and R₁₆ shown as hydrogen;

R₄, R₁₀ and R₁₆ are shown as --CH₃ ;

R₃, R₆, R₉, R₁₂, R₁₅ and R₁₈ being non-existent;

R₅ being non-existent;

R₁₁ and R₁₇ shown as carbonyl ##STR16##

G₁ being ##STR17## with:

R₁₉ being hydrogen; R₂₀ being --CH₂)₃ N(C₂ H₅)₂ ;

G₂ being --NR₁₉ R₂₀ R₂₁ with:

R₁₉ being non-existent; R₂₀ being hydrogen;

R₂₁ being --CH₂)₃ N⁺ (C₂ H₅)₂ CH₂ CH(OH)CH₂ --OCH₂ CH₂)_(x).sbsb.1 OCH₃where x₁ =20-700; and

G₃ being --OR₂₃ with;

R₂₃ being --CH₂)₂ ⁺ N(CH₃)₂ CH₂ CH(OH)CH₂ (OCH₂ CH₂)_(x).sbsb.2 OCH₃where x₂ ≅20-700 and n₁ ≅10-5,000; n₂ ≅0-20 and

n₃ ≅0-20, but n₂ and n₃ cannot both be zero.

B. ##STR18## with

R₃, R₅, R₆, R₉, R₁₁, R₁₂, R₁₅, R₁₇ and R₁₈ being non-existent;

R₁, R₂, R₄, R₇, R₁₀, R₁₃, R₁₄ and R₁₆ being hydrogen;

G₁ being --OCH₃ ;

G₂ being ##STR19## with R₈ being carbonyl ##STR20##

G₃ being --OCH₂ CH₂)_(x).sbsb.3 OCH₃ with x₃ ≅20-700; and

n₁ ≅10-1,000; n₂ ≅10-1,000; and n₃ ≅2-1,000.

C. ##STR21## with

R₁, R₂, R₄, R₇, R₈, R₁₀, R₁₃, R₁₄ and R₁₆ shown as hydrogen;

R₃, R₆, R₉, R₁₂, R₁₅, R₁₈, G₁, R₁₁ and R₃ being non-existent;

R₅ being ##STR22##

G₂ being ##STR23##

R₁₇ being ##STR24##

n₁, n₂, n₃ ≅0-500 with n₁ +n₂ +n₃ ≅10-600, but n₃ is not zero;

x₄ ≅20-700.

Examples of polymer units of Class II are:

A. ##STR25## wherein

R₂₅, R₂₆, R₂₉, R₃₁ and R₃₂ are hydrogen;

R₂₇ being ##STR26##

R₃₀ being ##STR27##

R₃₃ being ##STR28##

with G₄ and G₅ being ##STR29##

G₆ being ##STR30##

with x₅ and x₆ ≅0-3,000;

n₄ ≅10-5,000; n₅ and n₆ ≅0-2,500, but n₅ and n₆ are not both zero; andn₄ +n₅ +n₆ ≅10-10,000.

Examples of polymer units within Class III are:

A. ##STR31## wherein

R₃₄, R₃₈ and R₄₂ are non-existent;

R₃₅, R₃₉ and R₄₃ are hydrogen;

R₃₇, R₄₁ and R₄₅ are --CH₂ CH₂ -- (ethylene;

R₃₆ is --CH₂ CH₂ --N⁺ .tbd._(x).sbsb.7 with x₇ ≅10-200;

R₄₀ is --CH₂ CH(OH)CH₂ --OCH₂ CH₂)_(x).sbsb.8 OCH₃ with x₈ ≅10-200;

R₄₄ is --CH₂ CH₂ --N⁺ .tbd._(x).sbsb.9 with x₉ ≅10-200; and

n₇, n₈ and n₉ are each independently ≅10-1500.

B. ##STR32## wherein

R₃₄, R₃₈ and R₄₂ are non-existent;

R₃₅, R₃₆, R₃₉, R₄₃ and R₄₄ are --CH₃ ;

R₄₀ is --CH₂ CH(OH)CH₂ --OCH₂ CH₂)_(x).sbsb.10 OCH₃ with x₁₀ ≅10-700;

R₃₇ and R₄₁ are --CH₂ CH(OH)CH₂ --;

R₄₅ is ##STR33##

with x₁₁ ≅20-20,000; and

n₇, n₈ and n₉ being ≅0-500 but n₈ and n₉ are not both zero.

C.

One preferred group of polymeric units or monomeric units include thealkyl group of alkylene imines in which the alkyl or alkylene groupcontains about 2-4 carbon atoms, e.g., polyethyleneimine (PEI). Thistype of polymer can be prepared by homopolymerization orcopolymerization into either substantially linear or randomly branchedpolymers. Either type polymer can be grafted with branch chains usingthe same or a different alkylene imine or alkyl imine monomer orpolyalkyleneimine polymers. Other types of branching monomers orpolymers can also be attached to the backbone polymer chain such asoxygenated monomers or polymers, e.g. --O--R-- or --N--R-- wherein R isalkyl, aryl, alkenyl, cycloalkyl or combinations thereof with eachhydrocarbon radical having 1-10 carbon atoms arranged in a structure,combination or ratio to produce the desired hydrophilic-hydrophobicproperties. The randomly branched polyalkylimine can be used as abranched polymer as is or it may be further branched or substituted. Forthese and most preferred polymers and applications the degree ofbranching should be in the range of about 1-99%, preferably 10-35%, orone to 99 of each 100 potential branching sites shoud have a branchchain attached. For the polyalkylimine this would also mean that thenitrogen to which each branch was attached would be quaternized orprotonated, shown as follows for PEI: ##STR34##

Preferred molecular weight ranges for this class of polymer are about800-50,000,000 and preferably about 1,000-1,000,000 for WOR control,viscosifiers and mobility control of aqueous fluids.

Examples of polymer units within Class IV are:

A. ##STR35## wherein

R₄₇, R₅₀ and R₅₃ are non-existent;

R₄₆, R₄₉ and R₅₂ are hydrogen;

R₄₈ is ##STR36##

with x₁₂ ≅20-700;

R₅₁ is ##STR37##

with x₁₃ ≅0-700;

R₅₄ is ##STR38##

n₁₀ and n₁₁ ≅0-1500; n₁₂ ≅10-3000, but n₁₀ and n₁₁ are not both zero.

B. ##STR39## wherein

R₄₆, R₄₉ and R₅₂ are hydrogen;

R₄₇, R₅₀ and R₅₃ are non-existent;

R₄₈ is ##STR40## where A is any of the alpha substituents present innaturally occurring amino acids which comprise the polymeric polyamidesgenerally known as proteins. A detailed discussion of the chemicalnature of the alpha substituents and the structures of the polymericproteins can be found in a biochemistry text.

R₅₁ is CH₂ --O--CH₂ CHCONH₂)_(x).sbsb.14 H with x₁₄ ≅10-50,000;

R₅₄ is --CH₂ --₄ NH--CH₂ CH(OH)CH₂ --OCH₂ CH₂)_(x).sbsb.15 OCH₃ with x₁₅≅10-50,000; and

n₁₀ ≅10-3000; n₁₁ and n₁₂ are ≅0-1500 but n₁₁ and n₁₂ are not bothconcurrently zero.

Examples of polymer units within Class V are:

A. ##STR41## wherein

R₅₆ and R₅₉ are hydrogen;

n₁₅ is O or non-existent;

R₅₅ is --CH₂ CH₂ (OCH₂ CH₂)_(x).sbsb.16 OH and R₆₀ --CH₂ CH₂ (OCH₂CH₂)_(x).sbsb.17 OH with x₁₆ and x₁₇ being independently 0-100;

R₅₇ is --CH₂ CO₂ Na;

R₅₈ is --CH₂ CH(OH)CH₂ --OCH₂ CH₂)_(x).sbsb.18 OCH₃ with x₁₈ ≅10-700;and

n₁₃ ≅5-5000 and n₁₄ ≅1-1000.

B. ##STR42## wherein

R₅₆, R₅₈, R₅₉, R₆₁ and R₆₂ are --H;

R₅₅ is ##STR43##

a poly(substituted hexose unit) where x₁₉ is about 0-1000;

R₅₇ is --CH₂ CH(OH)CH₂ --OCH₂ CH₂)_(x).sbsb.20 OCH₃ with x₂₀ ≅10-700;

R₆₀ and R₆₃ are --CH₂ CHCONH₂)_(x).sbsb.21 and x.sbsb.22H with x₂₁ andx₂₂ ≅0-5000; and

n₁₃ +n₁₄ +n₁₅ ≧3.

Examples of polymer units within Class VI are:

A. ##STR44## wherein

R₆₅, R₆₆, R₆₉, R₇₁ and R₇₂ are hydrogen;

R₆₇ and R₇₀ are --CH₂ --; R₆₈ is --CH₃ ;

R₆₄ is ##STR45## with x₂₃ and x₂₄ being about 0-3000, but x₂₃ and x₂₄are not both zero;

X_(B), X_(C) and X_(D) are --O--; and

n₁₆ ≅1-5000; n₁₇ ≅0-5000; and n₁₈ ≅0-5000;

B. ##STR46## where

R₆₅, R₆₆, R₆₉, R₇₁ and R₇₂ are hydrogen;

R₆₇ and R₇₀ are methylene --CH₂ --; R₆₈ is --CH₃ ;

R₆₄ is ##STR47## with x₂₅ ≅0-5000 and and x₂₆ and x₂₇ ≅0-3000, but x₂₅,x₂₆ and x₂₇ are not all zero;

X_(B), X_(C) and X_(D) are --O--; and

n₁₆ ≅1-5000; n₁₇ and n₁₈ ≅0-5000.

One preferred class of polymer units from one or more of the aboveclasses are those in which the branch chain polymers contain polymerunits such as ##STR48## and combinations thereof wherein R₈₂ isindependently in each position defined the same as R₃ ; and wherein R₈₃is independently in each position defined the same as R₁. Within thisclass a preferred group of polymers are those in which the R₈₂ groupsare predominantly C₂ -C₄ alkylidene radicals such as ethylene, propyleneand/or butylene. These branch chains should preferably have molecularweights up to about 50,000 such as about 800-30,000. These branch chainscan contain an average of about 2-25,000 or even up to 50,000 polymerunits. The branch chains of any polymer can be substantially uniform ormixtures of different chain lengths and/or configurations can be used.Certain polyethyleneimine polymers as described herein can be used forclay stabilization or WOR alteration. For other uses these polymers,especially the lower molecular weights and ranges, should haveadditional branching or crosslinking. Certain other preferred polymersof these classes are useful in cements, aqueous fluids having a pH ofless than about 10 and especially in acidic media having a pH of lessthan about 6.5 or even 3.0.

These branch chains can be attached to various types of backbonepolymers. The backbone chain and branch chain can both containsubstantially the same type of polymer units or combinations of polymerunits. The branched polymer can have substantially different backbonepolymer chain and branch chain polymer units with each havingsubstantially different properties such as the hydrophilic-hydrophobicnature, ionic character or solubility in various fluids. For example,the backbone chain can be highly ionic (e.g., either anionic, cationic,amphoteric or a mixture thereof) with the branch chain being essentiallynonionic, yet being highly hydrophilic or solvatable in the presence ofaqueous fluid. The ionic groups can be in linear backbone chains, inpendent groups of the backbone chain or both. Another preferred polymercan have the backbone chain more hydrophilic and the ionic groups can bein the branch chains. Yet another preferred polymer can have portions ofbackbone chains and/or branch chains with the above descriptions. Theoverall branched polymer properties can make it highly water soluble oronly slightly water soluble. It might also be soluble in other fluidssuch as organic fluids or substituted organic fluids including polarsolvent such as alcohols (C₁ -C₁₈), organic acids, sulfonatedhydrocarbons, oxygenated hydrocarbons or polyol hydrocarbons.

Another preferred class of polymers from the above classes are thosepolymers which contain more than one type of polymer unit. Thesepolymers can be those defined by a single formula of the above eightclasses or by combining two of more formulas from different classes.This class of polymers includes those with at least one type of polymerunit derived from alkylacrylate, arylacrylate, alkyl acrylamide, arylacrylamide, alkyl aziridene, aryl aziridene, alkoxide, alkyl epoxide,the reaction product of ammonia or alkyl amine reacted with an alkyldihalide, an alkyldiepoxide, or combination thereof, or combinations ofthese polymer units. In these units the hydrocarbon radicals can contain1-10 carbon atoms. In certain units, such as the acrylate andacrylamide, when the hydrocarbon radical has zero carbon atoms it isnon-existent. In other units there may be more than one hydrocarbonsubstituent and the substituent may be in one of various positions ineach unit. A particularly preferred and surprisingly stable andeffective polymer for gelling aqueous fluid, especially acidic aqueousfluid, as well as for reducing WOR, are polymers and copolymerscontaining substantial amounts of methacrylate units in the backbonechain. These polymers with alkylidene oxide branches are essentiallypermanent and stable at high temperatures, even in high pressure steam.These polymers are also effective for controlling fluid loss fromaqueous fluids such as cements, treating fluids, fracturing fluids andacidizing fluids; for stabilizing clays in the presence of aqueousfluids; and for reducing friction loss when pumping various fluids."Stability" as used herein refers to use of the polymers for increasingviscosity of aqeuous fluids, especially for gelling acids for fracturingand/or acidizing, and means the polymer fluid mixture should maintainthe major portion of its viscosity for two hours at about 140° F. in 5%hydrochloric acid with no significant loss in viscosity or formation ofprecipitate.

Additional examples of polymer units within one or more of the aboveclasses are: ##STR49##

Some of these formula can be written in more general form as: ##STR50##

wherein R₈₄, R₈₅, R₈₆, R₈₇, R₈₈, R₉₀, R₉₁, R₉₂, R₉₃, R₉₄ beingindependently defined as R₁ herein;

wherein R₈₉, R₉₅, R₉₆, R₉₇, R₉₈ and R₉₉ are independently defined as R₃herein; and

wherein X₅, X₆ and X₇ are independently defined as G₁ herein.

Several preferred polymer units include the alkyl acrylates andacrylamides and substituted alkyl acrylates and acrylamides and can bedefined by the more general formula: ##STR51## wherein

R₁₀₀ and R₁₀₂ can be hydrogen, alkyl, aryl, hetero groups orcombinations thereof with each hydrocarbon radical containing about 1 to6 carbon atoms;

R₁₀₁, R₁₀₃ and R₁₀₄ can be hydrogen, iso or normal alkyl, aryl, heterogroups or combinations thereof with each hydrogen radical being selectedindependently and containing about 1 to 6 carbon atoms.

Preferred branch chains or R groups for these polymer units include--R₁₀₅ N═_(n) or --R₁₀₆ O--_(n), with R₁₀₅ and R₁₀₆ being an alkyleneunit having about 1-10 carbon atoms per each hydrocarbon radical and nis an integer up to about 50,000 and preferably up to about 2,000.

One particularly preferred class of polymers for altering aqueous fluidproperties, such as reducing WOR, gelling aqueous fluids, fluid losscontrol, and enhancing oil production, are those containing alkylacrylate backbone units and ethylene oxide branches such as thosedefined by the formula: ##STR52## with x being about 10 to 60,000,preferably 10 to 15,000; y being about 1 to 90,000, preferably 1 to5,000; and z being about 2 to 25,000, preferably 2 to 10,000; and A⁻ isan anion associated with the quaternary nitrogen.

These preferred polymer units can also have other substituents,especially on the carbon and nitrogen atoms. The polyethylene oxidechain, --OCH₂ CH₂ --_(z), can also be capped or terminated by hydrogen,hydroxyl, C₁ -C₆ oxyalkyl, C₆ -C₈ oxyaryl, oxy(2hydroxy-3-chloropropane) or oxy(-2,3-oxopropane) as well as the methoxygroup shown.

One particularly preferred class of polymers for altering aqueous fluidproperties, such as reducing WOR, gelling aqueous fluids and enhancingoil production, are those containing 2-hydroxypropyl N,N-dialkyl-aminebackbone units and acrylamide and/or epichlorohydrin reactedpolyalkoxide branches such as those defined by the formula: ##STR53##with

v being about 0-60,000 and preferably 0-2,000;

w being about 2-10,000 and preferably 2-1,000;

x being about 10-60,000 and preferably 10-10,000;

y being about 0-60,000 and preferably 0-2,000;

z being about 3-100,000 and preferably 3-30,000; and

A⁻ is an anion associated with the quaternary nitrogen.

These preferred polymer units can also have other substituentsespecially on the carbon and nitrogen atoms.

The polyalkyloxide chain (OR)_(w) can also be capped or terminated byhydrogen, hydroxyl, C₁ -C₆ alkyl, C₆ -C₁₀ aryl,oxy(2-hydroxy-3-chloropropane), or oxy(2,3-oxopropane) as well as themethoxy group shown.

One particularly preferred class of polymers for altering aqueous fluidproperties, such as reducing WOR, gelling aqueous fluids and enhancingoil production, are those containing methylene piperidinium backboneunits and epichlorohydrin reacted polyalkoxide branches such as thosedefined by the formula: ##STR54## with

x being about 10-50,000 and preferably 10-3,000;

y being about 1-10,000 and preferably 2-1,000; and

z being about 2-10,000 and preferably 2-1,000.

These preferred polymer units can also have other substituentsespecially on the carbon and nitrogen atoms.

The polyalkyloxide chain (OR)_(z) can also be capped or terminated byhydrogen, hydroxyl, C₁ -C₆ alkyl, C₆ -C₁₀ aryl,oxy(2-hydroxy-3-chloropropane), or oxy(2,3-oxopropane) as well as themethoxy group shown.

One particularly preferred class of polymers for altering aqueous fluidproperties, such as reducing WOR, gelling aqueous fluids and enhancingoil production, are those containing alkyl ether and butanedicarboxylate backbone units and epichlorohydrin reacted polyalkoxideand/or polyalkoxide such as those defined by the formula: ##STR55## with

u being about 10-60,000 and preferably 10-10,000;

v being 0-10,000 and preferably 0-2,000;

w being 2-10,000 and preferably 2-1,000;

x being about 10-60,000 and preferably 10-10,000;

y being 0-10,000 and preferably 0-2,000; and

z being about 2-10,000 and preferably 2-1,000.

These preferred polymer units can also have other substituentsespecially on the carbon and nitrogen atoms.

The polyalkyloxide chain (OR)_(w) can also be capped or terminated byhydrogen, hydroxyl, C₁ -C₁₆ alkyl, C₆ -C₁₀ aryl,oxy(2-hydroxy-3-chloropropane), or oxy(2,3-oxopropane) as well as themethoxy group shown.

PROCEDURE A Preparation of a Branched Polymer Containing PolyacrylamideBranches

1. To a three-neck 250 ml flask equipped with a condenser, stirringdevice, gas inlet tube and temperature probe, is added 50 cc ofdistilled water and 30 g of a commercially available polymer preparedfrom epichlorohydrin and dimethyl amine.

2. The flask is purged with nitrogen gas while 0.4 g isopropyl alcoholand 20 g of acrylamide monomer (as a 40% aqueous solution) is added. Thereaction contents are heated to 64° C.

3. Introduce 0.27 g of an azobisisobutyronitrile radical polymerizationinitiator and maintain temperature at 85° C. for 3 hours. The productconsists of a pale yellow to amber fluid with 2000 to 8000 cP viscosityon a #3 Brookfield spindle at 12 rpm, 25° C.

PROCEDURE B Preparation of a Backbone Polymer and Subsequent Grafting ofBranches to the Polymer

1. To a three-neck 500 ml flask equipped with a condenser, stirringdevice, gas inlet tube and temperature probe, heating mantle andaddition funnel is added 160 g of dimethyldiallylamine monomer (as a 40%aqueous solution) and 40 g diallylamine monomer. The pH of the reactionmixture is adjusted to approximately 4.0.

2. The flash is purged with nitrogen gas while the contents are heatedto 70° C.

3. 10 g of ammonium persulfate catalyst is dissolved in 100 g of waterand placed in the addition funnel. The catalyst is added in 5 equalportions every 30 minutes while the temperature is maintained at 70° C.The reaction mixture is then maintained at 80° C. for an additional 2hours. The reaction mixture is cooled and the nitrogen purge isdiscontinued. The reaction product is a viscous yellow fluid.

4. A quantity of product from Step 3 above is removed which represents1.76 g of active copoly(dimethyldiallyldiallyl)ammonium chloride. Tothis is added 2.6 g of active MPEO-epichlorohydrin adduct productprepared as described in Procedure C herein. Dilute this mixture withwater to a concentration of about 4% active polymer.

5. Adjust the pH to about 9.5 with 50% sodium hydroxide solution. Saltcan be added to reduce viscosity.

6. Place the polymer mixture in a sealed container and in a water bathat 60° C. for two hours to permit the reaction to proceed. Stirring canbe used to keep it pumpable but stirring may affect time to produce agiven viscosity product.

7. Dilute the branched or grafted copolymer to a concentration of about2% with water or salt solutions and shear the fluid with a mixer (e.g.high speed Hamilton Beach Blender) to a constant viscosity.

8. Read the viscosity if desired and use the resulting product fortesting effectiveness as a WOR chemical or as an acid gelling agent asdescribed in Procedures E through O.

PROCEDURE C Preparation of A Branching Agent Or A Polymeric Branch Chain

1. A methoxypolyethylene glycol or oxide (referred to herein as MPEG orMPEO), such as CARBOWAX®MPEG 5000, 0.04 moles or 200 gm, is added to athree-neck 500 milliliter flask equipped with a condenser, stirringdevice, gas inlet tube and temperature probe.

2. The flask is purged with nitrogen gas while the glycol is meltedusing a water bath at 65°-75° C.

3. The water bath is removed and 0.12 moles (11.1 gm) epichlorohydrin isadded and mixed by stirring for 15 minutes.

4. Boron trifluoride etherate is added and the temperature is keptbetween 65°-75° C. with cooling and heating when necessary.

5. The MPEO-epichlorohydrin reaction product (i.e., MPEG or MPEO-adduct)is stirred for one hour.

6. Excess epichlorohydrin is removed with a rotary evaporator and thebranching adduct or branching agent is diluted with an equal quantity ofwater.

PROCEDURE D Preparation of A Branched Copolymer From A CommerciallyAvailable Copoly(methylvinylether/maleic anhydride) Backbone

1. To a 250 ml three-necked flask equipped with a condenser, stirringdevice, heating mantle, and temperature probe, is added 90 cc of water,7.3 g of a high molecular weight mixed oxide polyglycol, and 1.4 g ofnonylphenol surfactant. The reaction contents are heated to 50° C.

2. To the stirred, heated reaction flask contents is added 1.3 g ofcommercially available methylvinylether/maleic anhydride polymer and thereaction heated for 4 hours. The result is an off-white fluid having5800 cP viscosity at 25° C. measured with a number 3 Brookfield spindle,at 12 rpm.

PROCEDURE E Preparation Of A Branched Copolymer From A CommerciallyAvailable Polydimethylaminoethylmethacrylate (i.e. PDMAEM)

1. Add the amount designated in Table 12 of the cationic backbonepolymer into a container, add the designated quantity of water and stiruntil the polymer is dissolved. Add the designated amount of branchchain adduct polymer and stir for three minutes.

2. Adjust the pH to about 9.5 with 50% sodium hydroxide solution. Saltcan be added to reduce viscosity.

3. Place the sealed container in a water bath at 60° C. for two hours topermit the reaction to proceed. Stirring can be used to keep it pumpablebut stirring may affect time to produce a given molecular weight orviscosity.

4. Dilute the branched or grafted copolymer fluid with 75 milliliters ofwater and shear the fluid with a mixer (e.g. high speed Hamilton-Beachblender) to a constant viscosity.

5. Read the viscosity using a Model 35 Fann Viscometer at 300 RPM,standard bob and sleeve in centipoises (cp or cps).

6. For testing the polymer effectiveness for gelling aqueous acid, addthe required amount of concentrated acid (see Tables 12, 13, 14, 15 and16) to the concentrated aqueous polymer mixture. Then dilute, ifnecessary, to the desired acid and polymer concentration with stirring.Measure the mixture viscosity on the Fann Viscometer as before (e.g.,1.5% active polymer solids concentration in 5% hydrochloric fluid).

PROCEDURE F Preparation of a Modified-Branched Polymer (PEI)

1. Add the desired amount of a commercially available branchedpolyethyleneimine polymer (molecular weight about 40,000 to 100,000) towater to make a 6% active polymer concentration of PEI.

2. Add an extending or branching agent as described in Table 19 (6%concentration) and stir while heating (pH>9-10) at 140° F. untilgelation occurs.

3. Dilute the viscous gel with hydrochloric acid to the desired acidconcentration.

4. Measure the apparent viscosity on a Model 35A FANN Viscometer, No. 1spring, standard bob and sleeve.

PROCEDURE G Evaluation Of Effectiveness Of Branched Polymer ForReduction Of Aqueous Fluid Flow

1. Place a small quantity of glass wool into the bottom of a 100milliliter (ml) buret.

2. Pour 50 ml of deionized water into the closed buret.

3. Place 5.0 grams (gm) of 8-12 mesh sand into the bottom of the buretfollowed by 25.0 grams of 20-40 mesh sand. Place 5.0 grams of 8-12 meshsand on top of the 20-40 mesh sand.

4. Tap the buret gently to obtain a 20-40 mesh sand pack length of 8-9centimeters (cm).

5. Drain off excess deionized water to the top of the 8-12 mesh pack andnote the level of the meniscus in the buret and record as zero level.

6. Place 25 ml of deionized water into the buret (use syringe orpipette) and record the time necessary for it to pass through the packand reach the zero level. This is Initial Time.

7. Prepare a (1000 parts per million [ppm] polymer solids) branchedpolymer solution in deionized water and adjust to a pH below about 5.0with an acid such as hydrochloric acid.

8. Introduce 100 cubic centimeters (cc) of the branched polymer treatingsolution and flow it through the buret to the zero level.

9. Follow the treatment with 75 ml of deionized water.

10 Repeat step 6; this is the Final Time.

11. Divide Initial Time by Final Time and multiply by 100 to get % ofinitial flow rate.

PROCEDURE H Preparation of A Branched Polymer In Situ

A portion of backbone polymer such as polyethyleneimine[MW˜40,000-100,000 gm/mole (g/m)] in an aqueous fluid is combined withan equal active weight of MPEO-eipchlorohydrin adduct (about 5000 g/m)prepared as described in Procedure C and diluted with water to about a5000 ppm total polymer concentration. The pH is adjusted to above about7 to 8. This solution is then either injected into the test core or theformation to be treated.

If treating a test core, Procedure I should be used; if treating aformation, Procedure N should be used, except that after the treatmentstage has been completed, the system must be allowed to remain staticfor a period of time determined by the temperature, e.g. 24 hours at160° F. After this curing time has been accomplished, the test media isreturned to production and changes in flow rates are noted.

PROCEDURE I Method of Evaluating Effectiveness Of Branched Polymer ForReduction Of Aqueous Fluid Flow Through A Clayey Sand Pack

A dry blend of sand was prepared by mixing 88 parts of about 70-170 meshsand with 10 parts of fine silica flour (smaller particle size thanabout 200 mesh) and two parts of smectite clay. This blend (100 gm) waspacked into a TEFLON® polymer lined test chamber (2.38 cm I.D.) or aHassler sleeve test chamber (2.38 cm I.D.). Approximately 25 cc of 6.7%brine solution was produced through the sand pack and the test chamberwas either shut in overnight or for two hours at 80° C. to insurecomplete hydration of clays. A brine solution (6.7% sodium chloride) wasproduced through the sand pack until equilibrium conditions wereachieved, i.e., no change in differential pressure (ΔP_(i)) and flowrate (Q_(i)). A solution of the chemical to be tested was then injectedthrough the sand pack in the opposite direction. Then production wascontinued until equilibrium conditions again existed and the flow rate(Q_(f)) and differential pressure (ΔP_(f)) noted. The percent retention(%K_(i)) of the initial permeability was then obtained by the followingexpression: ##EQU1## where: Q_(i) =initial flow rate; Q_(f) =final flowrate; ΔP_(i) =initial pressure drop across the chamber and ΔP_(f) =finalpressure drop or differential pressure. % reduction=100-%K_(i).

PROCEDURE J Determination Of Relative Oil Permeability In A Sand Pack

After the determination of the percent retention of initial brinepermeability (%K_(i)) by Procedure I, kerosene (2.7 cp) was producedthrough the sand pack. The flow rate and differential pressure werenoted. The percent of the oil permeability compared to the initial brinepermeability was calculated by: ##EQU2##

PROCEDURE K Determination Of Branched Polymer Effectiveness ForReduction Of Aqueous Fluid Flow Through A Core

A Berea sandstone core or limestone core (2.38 cm O.D.×10 cm) wasmounted into a Hassler sleeve test chamber (2.38 cm I.D.). Approximately25 cc of 6.7% brine solution was produced through the core and the testchamber was either shut in overnight or for 2 hours at 80° C. to insurecomplete hydration of clays. A brine solution (6.7%) was producedthrough the core until equilibrium conditions were achieved, i.e., nochanges in pressure and flow rate. A solution of the chemical to betested was then injected through the core in the opposite direction.Then production was continued until equilibrium conditions again existedand the flow rate and differential pressure noted. The percent of theinitial permeability was then obtain by the following expression:##EQU3## where: Q_(i) =initial flow rate and Q_(f) -final flow rate.

PROCEDURE L Determination Of Relative Oil Permeability In A Core

After the determination of the percent retention of initial brinepermeability (%K_(i)) by Procedure K, kerosene (2.7 cp) was producedthrough the core. The flow rate and differential pressure was noted. Thepercent of initial brine permeability to oil was calculated by: ##EQU4##

PROCEDURE M A Typical WOR Procedure

A typical WOR procedure is designed for 40 gallons of polymer mixtureper foot of perforations. This is done by diluting a concentratedbranched ionic polymer concentrate solution about 10:1-70:1 with water(e.g., formation water, brine or 2% potassium chloride solution), andthen adding about 20° Baume hydrochloric acid to adjust the pH to about3-6. After the tubing is pressure tested and the injection rateestablished, the branched polymer solution is pumped at about twobarrels per minute, followed by water. This procedure is repeated insequence until all the branched polymer solution is injected into thewell. After the last stage is pumped, water is pumped as an overflush.

PROCEDURE N

One recommended procedure uses about 30 pounds of branched ionic polymerin a concentrate solution (solids) per interval foot diluted about15:1-50:1. The treatment volume depends on the porosity and radialpenetration desired in the formation. Table 22 gives recommendedvolumes.

If the total water producing interval is not known, it is recommendedthat about a 10-30 foot penetration over the entire producing intervalbe used to determine treatment volume. If the total water producinginterval is known or a good estimate is available, then about a 30-50foot penetration into this interval is recommended. It may be assumed,for this calculation, that all treatment fluid will enter the waterproducing zone. For greater radical penetration a more dilute solutioncan be used.

The mixing water can be any compatible brine solution. Additives (e.g.,corrosion inhibitors, bactericides, surfactants, etc.) need to bechecked for compatibility.

The polymer should be added with mixing to the carrier fluid. Turningthe tank 2-4 times with a reciprocating pump or a turbine or ribbon typeblender should provide sufficient mixing. The pH should be adjusted to3-5 with hydrochloric acid or other acid.

An initial injection rate and injection pressure should be determinedusing water or other available aqueous fluid. The rate should be as highas feasible while maintaining a pressure which is below fracturingpressure. It may be necessary to decrease the injection rate in order toremain below the maximum allowed pressure. The branched ionic polymertreatment solution should be overdisplaced using an aqueous fluid, gasor a hydrocarbon such as water, nitrogen, or lease oil. The well can beimmediately returned to production.

Treatment Sequence

1. Select a candidate well with an available production history.

2. Evaluate proposed carrier fluids such as water, crude oil, etc. andwell production information.

3. Mix branched polymer solution.

4. Determine the injection rate and pressure using available fluid.

5. Pump branched polymer treatment solution through tubing, annulus orboth, maintaining a pressure below formation fracturing pressure. p 6.Over displace branched ionic polymer solution into the formation usingan available fluid such as an aqueous fluid, gas, hydrocarbon or mixturethereof.

7. Put well on production.

PROCEDURE O Example Or Procedure For Method of Reducing WOR (Water-GasRatio)

A dry sand pack (65 cm long×0.72 cm diameter) was prepared from a blendof 80 parts of 70-270 mesh sand, 15 parts silica flour and 5 parts ofsmectite. The equilibrium gas (methane) flow-rate through the dry packwas 3900 cc/min at 500 psi differential pressure. After saturating thesand pack with 6.7% NaCl solution, a maximum flow rate of 1020 cc/minmethane at 500 psi differential was achieved. This sand pack was thentreated with 100 ml of a 1,000 ppm solution of a water soluble, ionic,branched polymer (PDMAEM [800,000 to 1,000,000 MW grafted withpolyethylene oxide [5,000 MW] branches 1:1 backbone-branch ratio byweight). The flow to water was reduced more than 90% while the flow togas was 170% of the initial. Approximately 1,000 l of methane wasrequired to reestablish equalibrium flow conditions.

                                      TABLE 1                                     __________________________________________________________________________    Alteration Of Flow and Viscosity Properties By Polyethylenimine Polymers      With Branching And Molecular Weight Variation.sup.1                                                 Viscosity, Cps                                                                          Active Conc. Of                                                     Brookfield @ 25° C.                                                              Polymer  Test     Reduction                   Polymer       Molecular Wt.                                                                         of 5% Aqueous                                                                           In Treating                                                                            Temp.,                                                                            Extended                                                                           Of Water                    Identity      Range   Solution  Solution, %                                                                            °C.                                                                        Flow.sup.6                                                                         Permeability,                                                                         %                                                                             K.sub.oiB.sup.9     __________________________________________________________________________    PEI 12        1,200   3.1       1.0      27  Yes  0.0     ND.sup.2            (Dow Chemical Co.)                                16.0                        PEI 600       40,000-60,000                                                                         28        0.5      27  Yes  75.4    84.8                (Dow Chemical Co.)                                                            PEI 600       40,000-60,000                                                                         28        0.1      27  Yes  73.5    100.5               (Dow Chemical Co.)                                                            PEI 1000      50,000-100,000                                                                        1200      0.05     27  Yes  91.6    90.0                (Dow Chemical Co.)                                                            PEI 1000      50,000-100,000                                                                        1200      1.33     27  Yes  87.7    93.0                (Dow Chemical Co.)                                                            PEI 1000      50,000-100,000                                                                        1200      1.0      27  Yes  85.6    75.7                (Dow Chemical Co.)                                                            PEI 1000      50,000-100,000                                                                        1200      1.0      60  Yes  80.5    99.2                (Dow Chemical Co.)                                                            PEI 1000      50,000-100,000                                                                        1200      0.1      27  Yes  83.6    90.0                (Dow Chemical Co.)                                                            PEI 1000      50,000-100,000                                                                        1200      0.1      27  Yes  81.2.sup.3                                                                            93.2.sup.3          (Dow Chemical Co.)                                                            PEI 1000      50,000-100,000                                                                        1200      0.1      82  Yes  98.sup.4                                                                              140.sup.4           (Dow Chemical Co.)                                                            Polymin P     50,000-55,000                                                                         7         0.5      60  No   66.sup.4,7                                                                            ND.sup.2            (BASF)                                                                        EPOMIN P-1000 60,000-80,000                                                                         9         0.1      27  No    0.sup.4,7                                                                            ND.sup.2            (Japan Catalytic                                                              Chemical Co.)                                                                 EPOMIN P-1000 (Japan  108,000.sup.5                                                                           0.05     27  No   42.sup.4,7                                                                            ND.sup.2            Catalytic Chemical Co.)                                                       Polymer grafted with                                                          methyoxypolyethyleneoxide                                                     branches.sup.8                                                                __________________________________________________________________________     .sup.1 All flow tests involved clayey sand packs (88:10:2 parts by weight     [pbw] respectively of Oklahoma No. 1 sand, fine silica flour                  [≅-200 mesh] and bentonite) unless otherwise indicated.             .sup.2 ND -- Not Determined.                                                  .sup.3 Test sand consisted of a mixture of 2:10:88 pbw respectively of        bentonite, 70-170 U.S. mesh CaCO.sub.3 particles, fine silica flour and       Oklahoma No. 1 sand (U.S. Mesh 70-170).                                       .sup.4 Flow tests performed using a Berea core.                               .sup.5 Viscosity of a 2.0% aqueous solution.                                  .sup.6 All tests involved flowing fluids to a stabilized rate; however,       extended flow continued beyond this point up to 10,000 pore volumes on        same tests.                                                                   .sup.7 Core different from those used to test PEI 1000. Difference in cor     can cause some variation or difference in test results.                       .sup.8 Polymer grafted using procedures such as C and E with 1:1 backbone     polymer to branch polymer weight ratio.                                       .sup.9 % K.sub.oiB as determined in Procedure J or L.                         The data show that high molecular weight branched PEI polymers are            effective for altering permeability to aqueous fluids where low molecular     weight PEI is not effective and/or long lasting.                         

                                      TABLE 2                                     __________________________________________________________________________    Comparison Of Flow Property Changes                                           In Sands.sup.1 Using Linear Polyacrylamide                                    And Branched Polyethylenimine Polymers                                                         Active Polymer                                               Polymer    Test  Concentration In                                                                         Reduction of Water                                Identity   Temp., °C.                                                                   Treating Solution, %                                                                     Permeability, %                                                                         % K.sub.oiB.sup.5                       __________________________________________________________________________    Polyacrylamide.sup.4                                                                     24    0.05       23.sup.2  ND.sup.3                                (Calgon WC-500)                                                               PEI 1000   24    0.05       94.4      104                                     (Dow Chemical Co.)                                                            PEI 1000   60    0.5        98.1      123                                     (Dow Chemical Co.)                                                            PEI 1000   82    0.5        70.2      ND.sup.3                                (Dow Chemical Co.)                                                            __________________________________________________________________________     .sup. 1 Test sand was constituted by 85:15 parts by weight (pbw)              respectively of Oklahoma No. 1 sand and fine silica flour.                    .sup. 2 Linear polyacrylamide gave significant reduction in water             permeability but its effectiveness rapidly diminished (see Table 13).         .sup. 3 ND -- Not Determined.                                                 .sup. 4 20% anionic polyacrylamide.                                           .sup. 5 Determined according to Procedure J.                                   The data show that a branched PEI polymer is effective for reducing          permeability to an aqueous fluid and increasing permeability relative to      oil when compared to a polyacrylamide polymer.                           

                  TABLE 3                                                         ______________________________________                                        The Reduction Of Water Permeabilities After Treatment With                    PEI-1000 On Various Permeability Sand Packs.sup.1                                                    Permeability                                                                             Reduction                                   Oklahoma #1 Sand                                                                          Permeability                                                                             After      of Water                                    & Fine Silica Flour                                                                       of Sand    Treating   Permeability,                               Parts By Weight                                                                           (Darcy)    (Darcy)    %                                           ______________________________________                                        1:0         11.9       8.80       26.0                                        9.75:0.25   9.60       6.60       31.0                                        9.25:0.75   1.04       .035       96.5                                        9:1         .246       .030       87.5                                        8:2         .197       .003       98.5                                        7:3         .090       .004       95.5                                        ______________________________________                                         .sup.1 These tests were performed in Teflon.sup. ® polymer sleeve         consolidation apparatus at room temperature. Both initial and final           permeabilites were obtained from stabilized flow rates. Treatments were 7     cc of .5% PEI1000 with the pH adjusted to 4.                             

The above data demonstrates relative effectiveness of a particularpolymer as applied in loose sand packs of various permeabilities. Theperformance of other branched polymeric structures covered by theseteachings will vary with polymer and formation characteristics.Polymeric molecules may be varied in molecular weight, degree ofpolymeric branching, length of polymeric branches, etc. to achievedifferent effects and magnitudes of effectiveness dependent on thematrix to be treated.

                  TABLE 4                                                         ______________________________________                                        The Effect Of A Branched Polymer On Altering The Water                        Permeability Of A Clayey Sand Pack Subjected To Steam Flow                    Procedure                                                                     Step    Step Description Pack 1  Pack 2                                                                              Pack 3                                 ______________________________________                                        1       % of Initial water perm                                                                        100     100   100                                            at 70° F.                                                      2       Treatment volume of a                                                                          600     800   500                                            branch polymer (1000                                                          ppm) at 70° F. (cc)                                            3       % of initial water perm                                                                         .5      .8    .3                                            after treatment at 70° F.                                      4       Produced volume of                                                                             700     4000  2000                                           steam at 350° F. (cc)                                          5       % of initial water perm                                                                         .6     9.7   16.4                                           after subjected to                                                            steam flow                                                            6       Produced volume of                                                                             2400    2400  900                                            steam at 500° F. (cc)                                          7       % of initial water perm                                                                        1.1     1.4   1.1                                            at 70° F. after subjec-                                                tion to 500° F. steam                                          8       Volume of 15% HCl used                                                                         200     200   200                                            to clean sand pack (cc)                                               9       % of initial water perm                                                                        3.0     3.9   1.6                                            after acidizing                                                       ______________________________________                                    

Each of the three sand packs was composed of 88:10:2 parts by weight70-170 mesh sand, silica flour and smectite, respectively. Results ofthis evaluation indicate that this branched, water-soluble polymer [abranched methacrylate copolymer (MW˜1,000,000)] was effective inreducing water permeability in 350° F. to 500° F. dynamic steamenvironments. Data also shows that deposited branched polymers wereresistant to wash-off by acidic fluids. These fluids are often used tostimulate formation fluid production in hydrocarbon producingformations.

                  TABLE 5                                                         ______________________________________                                        Alteration Of Flow and Viscosifying Properties Based                          On Branched Polymer Characteristics                                           Molecular                                                                              Viscosity, Cps.                                                      Weight of                                                                              Of Polymeric Solution                                                                          % K.sub.i Using 0.05%                               MPEO**   2% In Fresh                                                                              1.5% In   Polymer in 6%                                   Branch   Water      5% HCl    NaCl*                                           ______________________________________                                        5000     161        71        3.1                                             2000     121        59        6.0                                              750      81        24        38                                               350      78        28        44                                              ______________________________________                                         *Alteration of flow properties in Berea core. K.sub.i = initial brine         permeability of core.                                                         **MPEO is methoxypolyethylene glycol or methoxypolyethlene oxide (Union       Carbide Carbowax  ®).                                                

A commercially available PDMAEM (molecular weight 600,000-800,000)constituted the backbone. Viscosity of the aqueous solution of thebackbone polymer is approximately 20 cps at 25° C. at 2% polymer solids.All grafted polymers were a 1:1 ratio by weight of MPEO to backbonepolymer. Less branching resulted with 5000 molecular weight MPEO thanwith 350 molecular weight MPEO grafts. Branched or grafted polymers wereprepared by Procedures C and E. Data in Table 5 shows that as the branchchain decreases, the number of branches increases and the %K_(i) goesfrom 3.1 to 44. Thus, the K_(i) is significantly affected by a few longbranch chains and even by a greater number of short branch chains. Thedata also shows that fewer longer molecular weight branch chains forthis particular polymer family are more effective for increasingviscosity of aqueous and aqueous acid fluids.

                                      TABLE 6                                     __________________________________________________________________________    Aqueous Fluid Diverting and Water Permeability Reduction Properties of        Methoxypolyethylene Oxide                                                     Branched PDMAEM - Simultaneous Injection Technique.sup.1                      Water                                                                         Permeability, Darcy                                                                             Reduction of Water                                                                      Test      Relative Effluent                       Test Sand                                                                           Before                                                                              After Permeability By                                                                         Composition                                                                             Volume Passing Through                  No.   Treatment                                                                           Treatment                                                                           Treatment, %                                                                            Parts By Weight                                                                         Each Sand, cc                           __________________________________________________________________________    1     0.762 0.016 97.9      88:10:2   173.9                                                               Oklahoma #1 Sand,                                                             fine silica flour                                                             and bentonite                                     2     0.481 0.028 94.2      88.9:11.1 188.6                                                               Oklahoma #1 Sand                                                              and fine silica                                                               flour                                             3     0.053 0.007 86.8      Berea core                                                                              47.7                                                                Horizontal                                                                    Permeability                                      4     0.011 0.004 64.6      Berea core                                                                              35.2                                                                Vertical                                                                      Permeability                                      __________________________________________________________________________     .sup.1 By the use of a common manifold setup fluid injection was made         simultaneously into all test sands of varying permeabilities. Injection       pressure on all test sands were the same. The treating fluids were            therefore permitted to enter each test sample inversely proportional to       the resistances encountered in each sample. The polymeric solution            treatment produced a more uniform injection profile of fluids into test       samples with permeability variation. Note that the permeability of Test       Sand 1 is 40 times that of Test Sand 4. During polymeric treatment only       four times as much fluid passed through Test Sand 1 as compared to Test       Sand 4. The data show a significant reduction in permeability to aqueous      fluid flow for all four samples which indicates the branched polymer is       effective for aqueous fluid loss control.                                

                  TABLE 7                                                         ______________________________________                                        Branched Polymer Properties - Their                                           Effect On Reducing Water Permeabilities                                       Backbone Polymer - PDMAEM                                                     Molecular Weight about 1,000,000 Reacted With                                 Branch Polymer - Methoxypolyethylene Oxide (MPEO)                             Molecular Weight: 5000                                                        Backbone Polymer:                                                                          Concentration of                                                                             Reduction Of                                      Branch Polymer Ratio                                                                       Polymer In     Brine                                             By Weight    Treating Solution, %                                                                         Permeability, %                                   ______________________________________                                        0:1          .05            0-5                                               1:10         .05            55                                                1:5          .05            76                                                1:2.5        .05            94                                                1:1          .05            96.9                                              1:0.5        .05            92                                                1:0.25       .05            99.4                                              1:0.25       .01            92                                                1:0.12       .05            89                                                1:0.03       .05            99                                                1:0.015      .05            71                                                1:0.008      .05            11                                                1:0.004      .05            13                                                1:1 Unreacted*                                                                             .05            5                                                 1:0          .05            0.0                                               ______________________________________                                         *For this test the backbone polymer (PDMAEM) was merely mixed with (not       reacted with) the MPEO polymer.                                               All tests were run at 66° C. using Berea cores. An 8% NaCl solutio     was used to place the polymeric solution.                                

Data in Table 7 shows that some branching is necessary and that forcertain polymers a small amount or degree of branching produces asignificant effect. As you increase the number of branches theeffectiveness increases up to a certain optimum point. This shows thateach polymer family has a critical range for the ratio of backbonepolymer to the number of branched chains. The first, next to the lastand last data lines of the three columns are for an unbranched polymeror polymer mixture and they show that the unbranched polymer does notproduce the unexpected effect on aqueous fluid permeability that thebranched polymer family does.

                  TABLE 8                                                         ______________________________________                                        Alteration of Flow Properties in Bedford                                      Limestone By Branched Polymers                                                             Concentration                                                                             Test    Reduction In                                              In Treating Temp.   Water                                        Polymer      Solution, % °C.                                                                            Permeability, %                              ______________________________________                                        Polyethylenimine                                                                           0.5         60       74*                                         PEI-1000                                                                      (Dow Chemical Co.)                                                            PDMAEM       .01         66      94                                           (1,000,000 MW)                                                                with grafted                                                                  polyethylene oxide                                                            (15,000 MW) branches                                                          1:1 backbone-branch                                                           ratio by weight**                                                             ______________________________________                                         *PEI-1000 was apparently washing off the limestone core, i.e., this is no     an equilibrium or stabilized value.                                           **Graft polymer can also contain some crosslinking.                      

Data show that at least two different cationic polymers with highmolecular weight branches and high molecular weight branched polymersare effective in reducing permeability to aqueous fluid.

                  TABLE 9                                                         ______________________________________                                        The Effect of Some Branched Polymers                                          In Calcium Carbonate (70-200 m) Packs                                                        Concentration                                                                             Reduction in                                                      (ppm)       Water Perm.                                        Treatment Polymer                                                                            In Brine    (%)                                                ______________________________________                                        A              1000        42                                                 B              1000        23                                                 C              1000        25                                                 A and C combined                                                                              500 ppm each                                                                             74                                                 A followed by C                                                                              1000 ppm each                                                                             72                                                 ______________________________________                                    

Where A is an equal mole ratio copolymer of maleic anhydride andmethylvinyl ether (˜500,000 g/m) grafted with an equal weight ofmethoxypolyethylene glycol (˜5000 g/m); B is an equal mole ratiocopolymer of maleic anhydride and methylvinyl ether (˜5000 g/m) graftedwith an equal weight of polyethylene oxide (˜5000 g/m); C is a polymerof dimethylaminoethylmethacrylate (˜800,000 g/m) grafted with an equalweight of methoxypolyethylene glycol-epichlorohydrin adduct (˜5000 g/m).

                                      TABLE 10                                    __________________________________________________________________________    Alteration Of Flow Properties By Branched And Unbranched Polymers                                             Pore Vol. Of                                                                          Reduction In                                                          Brine Injected                                                                        Water                                 No.                                                                             Polymer                       Thru Test Sand                                                                        Permeability, %                       __________________________________________________________________________       ##STR56##                    10      0.0                                     n ≅ 300                                                             poly(dimethyl-2-hydroxypropyl ammonium chloride).                              ##STR57##                    100     43                                      x ≅ 300                                                             y ≅ 30                                                              z ≅ 1000                                                            Graft copolymer of the first polymer having polyacrylamide                    branches.                                                                      ##STR58##                    10      0.0                                     n ≅ 100                                                             poly(dimethyl-2-butenyl ammonium chloride).                                    ##STR59##                    10      0.0                                     n ≅ 200                                                             poly(dimethyl diallyl ammonium chloride).                                      ##STR60##                    10      0.0                                     n ≅  3000                                                           poly(dimethylaminoethyl methacrylate) salt with an anion                      such as A.sup.-.                                                              [CH.sub.2CH.sub.2O] .sub.n    10      0-5                                     n ≅ 100                                                             poly(ethylene oxide)                                                           ##STR61##                    10,000  85                                      x ≅ 3000                                                            y ≅ 30                                                              z ≅ 100                                                             A graft copolymer of polymer No. 5 grafted with methoxy-                      polyethylene glycol epichlorohydrin adduct.                                    ##STR62##                    40       5                                      x ≅ 50,000                                                          y ≅ 15,000                                                          Partially hydrolyzed polyacrylamide or co(polyacrylamide                      sodium acrylate).                                                           __________________________________________________________________________

Data in Table shows that the branched polymers are effective forreducing permeability to aqueous fluid flow where the linear polymersare not.

                  TABLE 11                                                        ______________________________________                                        Water Wetting Characteristics Of Aqueous Solutions                            Of Various Polymers And Surfactants*                                                                   Contact Angle                                        Chemical                 (degree)                                             ______________________________________                                        Blank of Deionized Water 36                                                   Polyethylenimine Polymer 31.8                                                 PEI-1000 (Dow Chemical Co.)                                                   PDMAEM                   22.2                                                 Branched with MPEO adduct                                                     Diallyldimethylammonium chloride                                                                       35.6                                                 Polymer (Calgon TRO-522)                                                      Nalco-607 - A branched and crosslinked                                                                 39.0                                                 polyamine polymer (20,000-25,000 molecular                                    weight)                                                                       Nalco-108 - A condensation polymer of                                                                  44.5                                                 dimethylamine and epichlorohydrin                                             (5000 molecular weight)                                                       Anionic aromatic petroleum sulfate                                                                     16.5                                                 (water wetting)                                                               Cationic surfactant blend of quaternary amines                                                         134.0                                                (oil wetting)                                                                 ______________________________________                                         *All test solutions were at pH 4 with 1% polymer solids or 1% active          concentration.                                                           

Data in this table demonstrates that the branched cationic polymers arewater wetting and have some surface active characteristics. The contactangles were measured using a clean glass slide immersed in diesel oilwith the polymer or surfactant dissolved in deionized water.

For aqueous fluid treatment with certain branched polymers, the surfacetension is decreased, which also normally results in a lower interfacialtension between aqueous and organic or hydrocarbon fluids.

                  TABLE 12                                                        ______________________________________                                        The Influence Of A Branched Polymer                                           On The Relative Oil Permeability.sup.a                                                         Test #1   Test #2                                            Test Step        (untreated)                                                                             Polymer (treated)                                  ______________________________________                                        Initial water permeability (md)                                                                911       906                                                Polymer treatment (PV).sup.b                                                                    0         2                                                 Water permeability after                                                                       911        38                                                treatment (md)                                                                Oil permeability (md).sup.c                                                                     8        164                                                ______________________________________                                         .sup.a Produced crude oil, produced water and core material used were fro     the Ranger formation, Wilmington field, California.                           .sup.b A concentration of 1000 parts per million was used.                    .sup.c These oil permeabilities were taken at irreducible water               saturation.                                                              

The core samples were stabilized to flow with produced water, thentreated with the pore volume (PV) of polymer and the permeability wasmeasured with produced water and crude oil.

The data shows that the branched polymer treatment decreasedpermeability to aqueous fluid and increased permeability to oil flow.

                                      TABLE 13                                    __________________________________________________________________________    Alteration Of Flow Properties Of Various Polymers - Effectiveness vs          Extended Flow                                                                                                     Polymer                                                                             Pore Volumes of                                                                            Reduction In                                     Initial Permeability                                                                    In Treating                                                                         Injected Through                                                                           Permeability,.sup.c    Polymer             Test Solids                                                                         Of Test Solids, Md.                                                                     Solution, %                                                                         Treated Solids                                                                             %                      __________________________________________________________________________    Polyethylenimine    1.sup.a                                                                             100       0.5    8           60                     (Dow PEI-12)                               45          33                     Molecular Weight: 1200                     80           7                                                               120           0                     Polyethylenimine    Bedford                                                                             42.5      0.5   1000         65                     (Dow PEI-1000)      Limestone             2000         65                     Molecular Weight: 50,000-100,000          3000         60                                                               4000         58                     Polyacrylamide      2.sup.a                                                                             450       .05   120          51                     (Calgon WC-500)                           270          38                     20% Anionic                               380          29                                                               570          22                     Polyacrylamide      Berea 88        0.3    30          66                     (Dow J-217)         Sandstone              60          56                     Molecular Weight: 1,800,000               200          15                     13% anionic                               270          11                     5.8 Intrinsic viscosity                   270          11                     PDMAEM              Berea 95.5      0.01  190          88                     Molecular Weight: 600,000-800,000                                                                 Sandstone             1270         88                     Branched with MPEO adduct                 2108         87                     (5000 molecular weight)                   3427         86                     Backbone and branch polymers reacted      5949         85                     in a 1:1.75 weight ratio                  11580        83                                                               13499        88                     PDMAEM              Bedford                                                                             13.8      0.1   200          75                     Molecular Weight: 600,000-800,000                                                                 Limestone             400          75                     Branched with polyethylene glycol         600          75                     (Union Carbide Carbowax 20M-              800          75                     Molecular Weight: 15,000). Back-          1000         75                     bone and branch polymers reacted                                              in a 1:1 weight ratio.sup.b                                                   __________________________________________________________________________     .sup.a Test solids #1 consisted of 88:10:2 parts by weight respectively o     Oklahoma No. 1 sand, fine silica flour and bentonite. Test solids #2          consisted of 85:15 parts by weight respectively of Oklahoma No. 1 sand an     fine silica flour.                                                            .sup.b Some crosslinking may exist in the final polymer along with            branching. Some hydrophilic crosslinking in specific application areas ca     be advantageous.                                                              .sup.c Brine permeability.                                               

The data show that resistance to wash-off or stability varies with thepolymer structure and that the high molecular weight, branched polymersare highly stable or do not wash off after flushing with over 10,000pore volumes of aqueous fluid.

                  TABLE 14                                                        ______________________________________                                        Relative Quantities Of Backbone And Branch Polymer                                       Cationic Polymer     MPEO                                          Cationic   Solution             Adduct                                        Polymeric:Adduct                                                                         (10% Polymer Water   (50% Polymer                                  Weight Ratio                                                                             Solids) (gm) (ml)    Solids) (gm)                                  ______________________________________                                        1.50:0     30           45      0                                             1.25:0.25  25           49      1                                             1.00:0.50  20           53      2                                             0.75:0.75  15           57      3                                             0.50:1.00  10           61      4                                             0.25:1.25   5           65      5                                               0:1.50    0           69      6                                             ______________________________________                                    

                  TABLE 15                                                        ______________________________________                                        Viscosity Properties Of PDMAEM                                                Grafted With MPEO Adduct                                                                   Apparent Viscosity, cp at 25° C.                                         Water                                                          PDMAEM:MPEO 350**                                                                            (2% Active                                                                              5% HCl                                               Weight Ratio   Polymer)  (1.5% Active Polymer)                                ______________________________________                                        1.5:0          27        8                                                    1.25:0.25      82        25                                                   1.00:0.5        73*      32                                                   0.75:0.75       78*      28                                                   0.5:1.0        25        7                                                    0.25:1.25      14        3                                                      0:1.5         3        1                                                    ______________________________________                                         *Foamy                                                                        **A commercially available PDMAEM with a molecular weight of about            600,000-800,000. MPEO 350 is Union Carbide's methoxypolyethylene glycol o     oxide with a molecular weight of about 350 sold under the trademark           "CARBOWAX ®."-                                                       

The data shows that branching is necessary for a stable polymer to gelaqueous and aqueous acid fluids. The data also shows that the number ofbranches affect the efficiency or effectiveness of the branched polymerfor gelling aqueous fluids.

                  TABLE 16                                                        ______________________________________                                        Viscosity Of PDMAEM                                                           Grafted With MPEO Adduct                                                                    Apparent Viscosity, cp at 25° C.                         PDMAEM:MPEO 750**                                                                             Water       5% HCl                                            Weight Ratio    (2% Active) (1.5% Active)                                     ______________________________________                                        1.5:0           17          7                                                 1.25:0.25       39          28                                                1.0:0.5          52*        26                                                0.75:0.75       81          24                                                0.5:1.0          7          5                                                 0.25:1.25        3          1                                                   0:1.50         1          1                                                 ______________________________________                                         *Foamy.                                                                       **MPEO 750 is a Union Carbide CARBOWAX polymer having a molecular weight      of about 750.                                                            

The data shows the same effects as in Table 15 plus the effect of highermolecular weight or longer branch chains.

                  TABLE 17                                                        ______________________________________                                        Viscosity of PDMAEM                                                           Grafted With MPDO Adduct                                                      PDMAEM:MPEO  Apparent Viscosity (cps)                                         2000**       Water      5% HCl (1.5% Active)                                  Weight Ratio (2% Active)                                                                              Initial  24 hrs @ 60° C.                       ______________________________________                                        1.5:0         13         7       11                                           1.43:0.07     37        20        4                                           1.36:0.14    105        45       50                                           1.25:0.25    200        114      142                                          1.00:0.50     198*      127      152                                          0.75:0.75    121        59       80                                           0.50:1.00     75        20       44                                           0.25:1.25     7          3        8                                             0:1.50      3          1        1                                           ______________________________________                                         *Foamy.                                                                       **MPEO  molecular weight about 2000.                                     

The data shows the same effects as Tables 15 and 16 for higher molecularweight branch chains. The data also shows that the branched polymer isstable in acid at high temperatures for extended periods of time.

                  TABLE 18                                                        ______________________________________                                        Viscosity of PDMAEM                                                           Grafted With MPEO Adduct                                                      PDMAEM:PDEO  Apparent Viscosity (cps)                                         5000*        Water      5% HCl (1.5% Active)                                  Weight Ratio (2% Active)                                                                              Initial  24 hrs @ 60° C.                       ______________________________________                                        1.5:0        15          6        8                                           1.43:0.07    26         14       15                                           1.36:0.14    60         39       15                                           1.25:0.25    120        49       52                                           1.0:0.5      141        68       56                                           0.75:0.75    161        71       77                                           0.60:0.90    124        46       --                                           0.5:1.0      98         23       27                                           0.25:1.25    32          7        9                                           0.14:1.36     7          3       21                                             0:1.5       3          1        1                                            0.75:0.75**  8          4       --                                           ______________________________________                                         *MPEO 5000 is a CARBOWAX ®  polymer having a molecular weight of abou     5000.                                                                         **For the mixture of PDMAEM, no epichlorohydrin was reacted with the          polyethylene oxide polymer to prepare an adduct but the pH was adjusted t     about 9.5 and the polymer solution heated for two hours at 60° C.      as in Procedure E.                                                       

The data shows the same effects as Table 17.

                  TABLE 19                                                        ______________________________________                                        Viscosity Properties of Modified-Branched                                     Polymers (Polyethylenimine)                                                                             Apparent Viscosity,                                                           cp at 25° C.                                 Branched Polymer                                                                          Modifying Agent                                                                             (4% Active)                                         ______________________________________                                        Chemicat P-145.sup.a                                                                      Nalco PS 2007M.sup. c                                                                       114                                                 EPOMIN P-1000.sup.b                                                                       Nalco PS 2007M                                                                              79                                                  Chemicat P-145                                                                            Nalco R69M.sup. d                                                                           46                                                  Chemicat P-145                                                                            None           5                                                  EPOMIN P-1000                                                                             None           3                                                  ______________________________________                                         These branched Polymers are modified as in Procedure F.                       .sup.a Polyethyleneimine from Alcolac Incorp.                                 .sup.b Polyethyleneimine from Japan Catalytic.                                .sup.c Ethylene-propylene oxide copolymer reacted with epichlorohydrin.       .sup.d Polyethylene glycol 250 reacted with epichlorohydrin.             

                  TABLE 20                                                        ______________________________________                                        Effect of Branched Cationic Polymers on Reaction Time                         of 5% HCl with Limestone.sup.a                                                               Contact Time (min)                                                                          % HCl                                            Acid Solution  With Limestone                                                                              Remaining                                        ______________________________________                                        5% HCl          0            5                                                                5            2.6                                                             10            2.3                                              5% HCl Gelled With                                                                            0            5                                                Modified PEI.sup.b                                                                            5            3.4                                                             10            3.25                                                            30            3.0                                                             45            2.8                                              ______________________________________                                         .sup.a Bedford Limestone                                                      .sup.b EPOMIN P1000 modified with ethylenepropylene oxide copolymer           epichlorohydrin adduct (4% active solution) as described in Procedure F. 

                  TABLE 21                                                        ______________________________________                                        Viscosity And Stability Of Various Polymers In Water And Acid                                  Apparent Viscosity (cps)                                                             5% HCl                                                                 Water  (1.5% Active)                                                            (2%              2 hrs                                     Polymer            Active)  Initial @ 60° C.                           ______________________________________                                        Polyvinyl alcohol  42       35      6                                         VINOL 1540 (Air Products &                                                    Chemicals, Inc.)                                                              poly(2-acrylamido-2-methyl propyl                                                                 55*     35      28                                        sulfonate)                                                                    AMPS (Lubrizol Company)                                                       Polyvinylpyrrolidone                                                                             35        5      6                                         PVP (GAF Corporation)                                                         Copolymer of acrylate (30%)                                                                      135      22      **                                        and acrylamide (70%)                                                          Copolymer of AMPS (20%)                                                                          115      37      12                                        and acrylamide (80%)                                                          Copolymer of acrylamide (70%)                                                                    120      62       9**                                      and N,N,N--trimethylaminoethyl                                                methacrylate                                                                  Copolymer of acrylamide (70%)                                                                    78       10      **                                        and N,N--dimethylaminoethyl                                                   methacrylate                                                                  ______________________________________                                         *Foamy.                                                                       **Polymer precipitated.                                                  

The data shows the effectiveness and stability of various linearpolymers in aqueous and aqueous acid fluids for extended times at hightemperature.

                  TABLE 22                                                        ______________________________________                                        Radial Penetration Into A Formation vs. Porosity                                         Radial Treatment                                                                           Treatment Volume                                      Porosity   Distance     Per Interval Ft.                                      (%)        (ft)         (bbl/ft)                                              ______________________________________                                        10         10           5.6                                                   10         20           22                                                    10         30           50                                                    10         40           90                                                    10         50           140                                                   20         10           11.8                                                  20         20           44.7                                                  20         25           70                                                    20         30           101                                                   20         40           179                                                   20         50           280                                                   30         10           16.8                                                  30         20           67                                                    30         30           151                                                   30         40           269                                                   30         50           420                                                   ______________________________________                                    

                                      TABLE 23                                    __________________________________________________________________________    Development Well Treatment                                                    This developmental production well is located on a waterflood project         and had been shut in due to excessive water production. It was put back       on production in order to establish initial production data. Fluid entry      surveys were performed prior to and after WOR polymer treatment. This         well was gravel packed and has 839 net feet producing. The treatment          with 30 drums of concentrated polymer solution of a cationic polymer          with nonionic branches diluted 1:40 with injection water gave about 1200      PSI increase in injection pressure. This solution was overdisplaced           with 350 barrels of injection water.                                          Production Rate                                                                               Calculated                                                                          Pressure  Productivity                                  Time                                                                              Gross                                                                             Water                                                                             Oil Water FOP*                                                                              Drawdown                                                                            Index                                         (days)                                                                            (BPD)                                                                             (BPD)                                                                             (BPD)                                                                             (BPD) (ft)                                                                              (PSI) (BPD/PSI)                                     __________________________________________________________________________    Initial                                                                           4310                                                                              --   55       1500                                                     0  5200                                                                              5145                                                                               55 5145  1725                                                                               46   113                                            1  4183                                                                              4094                                                                               89 --    --  --    --                                             2  3995                                                                              3929                                                                               66 495   954 365   11.0                                           6  5004                                                                              4937                                                                               67 484   704 469   10.7                                           7  4867                                                                              4782                                                                               85 469   704 469   10.4                                           8  4823                                                                              4721                                                                              102 --    --  --    --                                             9  4821                                                                              4717                                                                              104 442   649 491   9.8                                           10  4817                                                                              4723                                                                               94 433   624 502   9.6                                           11  4815                                                                              4711                                                                              104 441   649 491   9.8                                           12  4814                                                                              4695                                                                              119 424   604 510   9.4                                           13  4794                                                                              4677                                                                              117 422   604 510   9.3                                           15  4628                                                                              4520                                                                              108 --    --  --    --                                            16  4227                                                                              4118                                                                              109 356   549 533   7.9                                           17  4701                                                                              4587                                                                              114 --    --  --    --                                            18  4732                                                                              4596                                                                              136 389   524 543   8.7                                           19  4713                                                                              4567                                                                              146 --    --  --    --                                            20  4684                                                                              4542                                                                              142 --    --  --    --                                            21  4660                                                                              4519                                                                              141 --    --  --    --                                            22  4663                                                                              4520                                                                              143 --    --  --    --                                            23  4616                                                                              4481                                                                              135 --    --  --    --                                            24  4624                                                                              4474                                                                              150 362   464 568   8.1                                           25  4625                                                                              4479                                                                              146 --    --  --    --                                            26  4593                                                                              4439                                                                              154 --    --  --    --                                            27  4578                                                                              4437                                                                              141 --     764*                                                                             --    --                                            28  4704                                                                              4534                                                                              170 --    --  --    --                                            29  4676                                                                              4491                                                                              185 --    --  --    --                                            30  Downhole breakdown                                                            Pump on                                                                   31  5065                                                                              5026                                                                               39 --    1500                                                                              140   36.2                                          32  5419                                                                              5314                                                                              105 --    --  --    --                                            33  5092                                                                              4965                                                                              127 --    --  --    --                                            34  5193                                                                              5106                                                                               87 --    --  --    --                                            35  5160                                                                              4864                                                                              296 --    --  --    --                                            36  4493                                                                              4460                                                                               33 --    --  --    --                                            37  5112                                                                              4780                                                                              332 --    565 527   9.7                                           38  5032                                                                              4755                                                                              277 --    --  --    --                                            39  5131                                                                              4735                                                                              396 --    565 --    --                                            40  4355                                                                              4099                                                                              346 --    565 --    --                                            41  5063                                                                              4700                                                                              363 --    --  --    --                                            42  5027                                                                              4686                                                                              341 --    515 547   8.6                                           43  4970                                                                              4673                                                                              297 --    --  --    --                                            45  4979                                                                              4677                                                                              302 --    --  --    --                                            46  4985                                                                              4641                                                                              344 --    --  --    --                                            48  4964                                                                              4579                                                                              385 --    405 --    --                                            49  4811                                                                              4606                                                                              205 --    --  --    --                                            50  4487                                                                              4417                                                                               70 --    --  --    --                                            Fluid Entry                                                                   51  4850                                                                              4608                                                                              242 --    515 --    --                                            52  4807                                                                              --  193 --    --  --    --                                            53  4892                                                                              --  363 --    --  --    --                                            54  4783                                                                              4537                                                                              246 --    405 --    --                                            55  4790                                                                              4530                                                                              260 --    430 --    --                                            56  4782                                                                              4536                                                                              246 --    405 --    --                                            57  4737                                                                              4460                                                                              277 --    --  --    --                                            58  4730                                                                              4508                                                                              222 --    310 --    --                                            59  4738                                                                              4588                                                                              250 --    --  --    --                                            60  4707                                                                              4481                                                                              266 --    515 --    --                                            65  4958                                                                              4411                                                                              547 --    --  --    --                                            66  4732                                                                              4411                                                                              321 --    --  --    --                                            67  4717                                                                              4378                                                                              339 --    --  --    --                                            68  --  --  --  --    310 --    --                                            90  4800                                                                              --  355 --    400 --    --                                            __________________________________________________________________________     *FOP is feet of liquid over pump.                                        

                                      TABLE 24                                    __________________________________________________________________________    Developmental Well Treatment                                                  This development treatment well is located on a waterflood project.           It has been gravel packed and has 571 net feet producing fluid. Several       test and fluid entry surveys have been run both before and after the WOR      polymer treatment. The initial oil production rate varied. The WOR            polymer treatment consisted of 24 drums of concentrated polymer solution      of a cationic polymer with nonionic branches diluted 1:48 with injection      water with a 1200 barrel overdisplacement of injection water.                 Production Rate           Pressure                                            Time                                                                              Gross                                                                             Water                                                                             Oil Water:Oil                                                                           Gas FOP                                                 (days)                                                                            (BPD)                                                                             (BPD)                                                                             (BPD)                                                                             Ratio (mdf)                                                                             (ft) Comments                                       __________________________________________________________________________    Initial                                                                           2057                                                                              --  40-73                                                                             50-27 --  480                                                  0  2075                                                                              2006                                                                              69  29    16  482                                                   1 2176                                                                              2084                                                                              92  --    --  --                                                   2  1689                                                                              1599                                                                              90  --    --  --                                                   3  1466                                                                              1393                                                                              73  --    21  147                                                  4  1325                                                                              1266                                                                              59  --    --  --   put on 24/64 choke                                                            total pressure =                                                              300 PSI.                                        5  1252                                                                              1190                                                                              62  --    --  --                                                   6  --  --  --  --    --  146  Took choke out.                                 7  1174                                                                              1119                                                                              55  --    --  --                                                   8  1147                                                                              1106                                                                              41  --    --  --                                                   9  --  --  --  --    --  447                                                 10  --  --  --  --    --  --   Pump went down.                                11  1718                                                                              1669                                                                              49  --    --  --                                                  12  1481                                                                              1404                                                                              77  --    --  --                                                  13  1326                                                                              1266                                                                              60  --    --  359  Pump cycling                                   15  --  --  --  --    --  294                                                 16  1214                                                                              1157                                                                              57  --    --  --                                                  17  1186                                                                              1146                                                                              40  --    --  --                                                  18  1165                                                                              1108                                                                              57  --    --  294                                                 19  1144                                                                              1100                                                                              44  --    --  --                                                  20  1129                                                                              1066                                                                              53  --    --  --                                                  21  1106                                                                              1052                                                                              54  --    --  --                                                  22  1094                                                                              1041                                                                              53  --    --  --                                                  25  1057                                                                              1011                                                                              46  --    --  214                                                 26  1054                                                                              1008                                                                              46  --    --  --                                                  27  1045                                                                               993                                                                              52  --    --  --                                                  28  1031                                                                              --  34  --    --  274                                                 30  1016                                                                              --  52  --    --  --                                                  31  --  --  --  --    --  274                                                 32  1015                                                                               980                                                                              35  --    --  --                                                  33  1013                                                                               962                                                                              31  --    --  --                                                  34  1014                                                                               973                                                                              41  --    --  --                                                  34  Ran tool in for fluid entry survey but found well not stabilized.         35   830                                                                               824                                                                               6  --    --  674                                                 36   732                                                                               704                                                                              28  --    --  674                                                 36  1180                                                                              1107                                                                              73  --    --  --                                                  37  1125                                                                              1076                                                                              49  --    --  --                                                  38  1117                                                                              1070                                                                              47  --    --  --                                                  39  1119                                                                              1064                                                                              55  --    --  274                                                 40  Ran tool in for fluid entry survey.                                       40 am                                                                              900                                                                               880                                                                              20  --    --  --                                                  40 pm                                                                              900                                                                               860                                                                              40  --    --  --                                                  40  Ran fluid entry survey.                                                   42  1167                                                                              1119                                                                              48  --    --  --                                                  43  1148                                                                              1110                                                                              38  --    --  --                                                  44  1138                                                                              1083                                                                              55  21    --  --                                                  45  --  --  --  --    --  214                                                 60  1020                                                                              --  52  19    --  280                                                 __________________________________________________________________________

                  TABLE 25                                                        ______________________________________                                        Developmental Well Treatment                                                  This well was an old flowing well with a bottom hole static                   temperature (BHST) of about 104° C. with five feet of                  perforations at 11,446 feet. Four drums of heated concentrated                polymer solution of a cationic polymer with nonionic                          branches was used at a dilution of 1:30. This was over-                       displaced with 300 barrels of gun barrel water.                               Production Ratio            Pres-                                             Time  Gross   Water   Oil   Water:Oil                                                                             sure   Com-                               (days)                                                                              (PPD)   (BPD)   (BPD) Ratio   (PSI)  ments                              ______________________________________                                        Initial                                                                             1425    --      28    50      525    24/64                                                                         choke                              0     1425    1397    28    50      525    24/64                                                                         choke                              1     1242    1217    25    29      --                                        2     1260    1234    26    47      560                                       3     1284    1220    64    19      825                                       3     1296    1231    65    19      800                                       5     1240    1178    62    19      800                                       6     1260    1197    63    19      800                                       7     1254    1191    63    19      800                                       12    1211    1150    61    19      --                                        13    1658    1575    83    19      560    28/64                                                                         choke                              15    1451    1378    73    19      642    25/64                                                                         choke                              50    1400    --      73    18      642    25/64                                                                         choke                              ______________________________________                                    

                  TABLE 26                                                        ______________________________________                                        Development Well Treatment                                                    This well had ten feet perforated at 10,000 feet and was on gas-lift.         The treatment was performed using 12 drums of concentrated                    polymer solution of a cationic polymer with nonionic branches                 diluted 1:19 with preheated gun barrel water and overdisplaced                with 300 barrels of gun barrel water.                                         Production Rate                                                               Time   Gross    Water    Oil    Water:Oil                                     (days) (BPD)    (BPD)    (BPD)  Ratio   Choke                                 ______________________________________                                        Initial                                                                               642      629     13     49                                             1      580      493     87     --                                             2     1297     1297      0     --                                             3     1376     1348     28     --                                             4     1318     1292     26     --                                            16     1119     1097     22     --                                            18     1431     1403     28     --                                            29     1431     --       --     31      48/64                                 15     1431     --       28     50                                            ______________________________________                                    

                                      TABLE 27                                    __________________________________________________________________________    Developmental Well Treatment                                                  Time  Oil Water                                                                             Water:Oil                                                                           API  Fluid                                                                             Gross                                                                             Fluid Level                                  (days)                                                                              (BPD)                                                                             (BPD)                                                                             Ratio Gravity                                                                            Level                                                                             Fluid                                                                             Differential                                 __________________________________________________________________________    Before                                                                              36  1270                                                                              35    17.6 2548                                                                              1306                                                                               0                                           Treat-                                                                        ment                                                                           8    23  1508                                                                              --    20.3 2935                                                                              1531                                                                              387                                           9    37  1514                                                                              --    20.3 3062                                                                              1561                                                                              518                                          13    49  1288                                                                              --    20.3 3126                                                                              1337                                                                              578                                          15    43  1291                                                                              --    20.3 3126                                                                              1334                                                                              578                                          18    47  1447                                                                              --    20.3 3222                                                                              1494                                                                              674                                          21    61  1470                                                                              24    20.4 3286                                                                              1531                                                                              738                                          __________________________________________________________________________

                  TABLE 28                                                        ______________________________________                                        Developmental Well Treatment                                                  This well was treated with eight drums of concentrated polymer of             a cationic polymer with nonionic branches dissolved in 150                    barrels of NH.sub.4 Cl water with one 25-barrel spacer and                    overdisplaced with 175 barrels of lease brine.                                ______________________________________                                        Production Data             GL      Tubing                                    Time  Gross   Water   Oil   Water:Oil                                                                              Press.*                                                                            Pressure                            (days)                                                                              (BPD)   (BPD)   (BPD) Ratio   (PSI) (PSI)                               ______________________________________                                        Prior to                                                                            1180    1164    16    73      --    --                                  Treatment                                                                      2    1066    1040    26    40      800   150-350                                   1156    1128    28    40      780   120-430                              4    1282    1266    16    79      780-800                                                                             120-430                              7    1310    1296    14    93      785   125-430                             22    1298    1279    26    50      --    --                                  ______________________________________                                              Gross Injected   Gas Recovered                                                (MCF)            (MCF)                                                  ______________________________________                                        33    240              203                                                    34    209              267                                                    35    209              249                                                    37    209              244                                                    ______________________________________                                         *GL is gas lift pressure at the surface.                                 

                  TABLE 29                                                        ______________________________________                                        The Effect Of Injection Rate Through A                                        Perforation Tunnel On A Branched Polymer Solution.sup.a                       Polymer         Injection                                                                              Percent of                                           Concentration   Rate     initial Polymer                                      (ppm)           (gal/min.)                                                                             Effectiveness.sup.b                                  ______________________________________                                        1000 (unsheared)                                                                              0        100                                                  1600            1        102                                                  1600            3        109                                                  1600            11       102                                                   800 (unsheared)                                                                              0        100                                                   800            1        103                                                   800            3        110                                                   800            11       113                                                  ______________________________________                                         .sup.a Treatment solution was pumped through a simulated perforation          tunnel (3/8" I.D. × 3" pipe) at various rates and samples were          taken. These samples were evaluated and the results reported are based on     the unsheared polymer treating solution for reducing water permeability o     a Berea sandstone.                                                            .sup.b Percent of initial WOR effectiveness.                             

The data shows that the branched polymer is not significantly affectedor sheared by rapid pumping through a perforation.

We claim:
 1. A method of treating a subterranean particulate formationto alter the relative mobilities of oil and water in and through theformation comprising contacting the formation with a branched organicpolymer dissolved or dispersed in an aqueous carrier fluid in an amountsufficient to provide a concentration of from about 0.005 to about 1percent by volume of said carrier fluid and for a period of timesufficient for the polymer to absorb on or otherwise attached to theformation, the branched organic polymer having a molecular weight offrom about 900 to about 50,000,000 and having the structural formula:##STR63## wherein: v is in the range of from about 10 to about 15,000;wis in the range of from about 1 to about 5,000; z is in the range offrom about 2 to about 10,000; and A⁻ is an anion or anionic groupassociated with the quaternary nitrogen.
 2. The method of claim 1wherein the carrier fluid is an aqueous saline solution.
 3. The methodof claim 1 wherein the carrier fluid is an aqueous acid solution ofhydrochloric, hydrofluoric, nitric, sulfuric, phosphoric, acetic,formic, hydroxyacetic, sulfamic, citric, fumaric, oxalic, sodiumdihydrogen phosphate and mixtures thereof.
 4. The method of claim 1wherein the molecular weight of said backbone chain is in the range offrom about 1000 to 5,000,000.